Social Media and Inﬂuencer Marketing for Promoting Sustainable Tourism Destinations: The Instagram Case

: Instagram is a critical tool for the selection of tourism destinations. Instagram travel inﬂuencers seem to play a signiﬁcant role in this process, often using geo-location data to make their posts even more impactful. However, there is no evidence of them performing such a role in sustainable destinations, although these destinations are increasing and to a large extent are the future in tourism. This paper aspires to shed light in this area focusing on sustainable destinations. Speciﬁcally, the purpose of this paper is to examine (a) the role of Instagram travel inﬂuencers in shaping users’ opinions of a sustainable destination and (b) the importance of geo-location data used by inﬂuencers to the users’ selection of such a destination. Thirty sustainable tourism destinations, as posted between 2017 and 2019, were selected for examination by using 10 Instagram travel macro-inﬂuencers’ power derived from their followers’ interactions on posts. The study used a mixed method approach combining cross-sectional and quantitative data analysis. Panel data and a multiple hierarchical analysis using SPSS Statistics were implemented to test the hypotheses. Finally, a regression model was used to try to identify the relationship between geo-location data and the selection of sustainable tourism destinations. The ﬁndings show that Instagram travel inﬂuencers, as social media communicators, are positively related to the selection of a sustainable destination. However, the use of geo-location data by Instagram travel inﬂuencers does not enhance travelers’ intention for such a choice.


Introduction
The openness of a destination to international markets is considered a key strategy for generating income from abroad, attracting foreign direct investments, boosting its brand image globally, and strengthening its regional competitiveness and economic growth [1]. Under this prism, intensive and, simultaneously, low-cost marketing efforts have become a challenging task for making a destination attractive globally [2]. The role of sustainability in this context is considered vital, as it can be considered a part of a destination's overall image [3,4]. Travelers themselves contribute to promoting and keeping a destination sustainable with their behavior and their story posts on social media [5].
Nowadays, social media platforms have an important role in destination marketing strategies, providing travelers with the opportunity to share their travel experiences in real time [6]. Regarding tourism destinations, Instagram offers a wide range of benefits, especially when financial and marketing resources are limited [7]. As of January 2022, Instagram is the third (after Facebook and YouTube) among the top leading social networking sites worldwide with 1478 million active users and the first selected media platform for marketing planned campaigns (the advertising expenditure in Instagram is 60% higher than the other social media platforms) [8].
Moreover, Instagram is well known as the first social media platform that offered the possibility of social interactions with other users acting as real-life friends [9]. This parasocial engagement, i.e., the engagement occurred through digital interaction between a viewer and a character that creates a virtual/imagined and trustful relationship [9], has led Instagram to become one of the most popular platforms in contemporary influencer marketing literature [10]. As a result, Instagram users with high engagement levels have been first perceived as peers by their followers, presenting significant persuasive/influence power [11].
Influencer marketing has seen the most noteworthy growth on Instagram due to its wealth of visual affordances and shopping/selecting features [11]. In fact, Instagram has been ranked as the favorite platform of marketers for influencer marketing [12]. According to Statista's findings for 2022 [13], Instagram alone accounts for over 500,000 active influencers with more than 15,000 followers, which constitutes 39% of all Instagram accounts. Among this group of active influencers, 81% are followed by anywhere between 15,000 and 100,000 people [13].
The enormous use of Instagram combined with the lifestyle of influencers (by sharing their traveling moments and memories online) has boosted influencer marketing [6]. Expenditure on influencer marketing has escalated from USD 1.7 billion in 2016 to USD 16.4 billion in 2022 [14]. Moreover, 84% of marketers characterize influencer marketing as one of the most effective tools in current marketing and branding strategies globally [15]. As a result, influencer marketing can be perceived as a very effective destination marketing tool not only for cities, places, or countries but also for National Tourism Organizations (NTOs), Destination Management Organizations (DMOs), travel agencies, venues, or hotels [16]. In contemporary tourism literature, digital influencers consist of key destination spokespersons who stimulate tourists' preferences and boost the image of a destination [4]. However, there seem to be no studies-at least according to authors' knowledge-that examine the impact of travel influencers in sustainable destinations. This would be interesting as these destinations offer many advantages of economic and social development with a low environmental burden and are constantly multiplying and present a growing interest [17].
In addition, the clear motives of users for the selection of sustainable destinations still seem to remain vague [7]. With the growing popularity of Instagram and the significance of influencer marketing in sustainable tourism, additional information and methods of data gathering that have not yet been examined in depth could support the marketing strategies of a destination [16]. Existing studies almost exclusively use traditional methods, such as questionnaires, for these purposes [18]. However, geo-location social media data, in particular, seem to be among the upcoming data collection trends for studying the travel demand of a destination [19], seeing as they represent check-ins at the venue, shared content, and/or hashtags that are connected to users', travelers', and travel influencers' geo-locations [20]. Moreover, these data have been considered beneficial elements for further boosting a destination's brand image, which is usually represented by geographic elements, such as coastal, mountainous, rural, and urban areas [21]. However, no evidence from sustainable destinations exists, although these elements could be part of the overall sustainability factor that is essential for a destination's internationalization in an increasingly competitive tourism market, usually measured at a national level [17].
This study tries to enhance the existing literature regarding the role of Instagram influencers on the decision-making process of travelers, as well as to further diminish the research gap related to the importance of new innovative and low-cost promotion techniques that have not been studied yet in contemporary sustainable destination and international marketing strategies, such as the use of location-based social media data [18]. In addition, the study aspires to enhance the existing academic literature on parasocial relationship theory under the spectrum of influencer marketing and geo-location data that recent research has not examined yet for sustainable tourism destinations [22]. Therefore, the purpose of this paper is to examine (a) the role of Instagram travel influencers in shaping users' opinions of a sustainable destination and (b) the importance of geo-location data used by influencers to the users' selection of such a destination. The paper tries to answer the following research questions: RQ1. Do Instagram travel influencers shape users' decisions on choosing sustainable destinations? RQ2. Do geo-location data on Instagram travel influencers' posts prompt users' selections regarding sustainable tourism destinations?
By addressing these research questions, the paper aims at shedding light on the potential of Instagram travel influencers and geo-location data to promote sustainable tourism. The findings of this study will give tourism and destination marketers insightful information that they may utilize to promote more environmentally friendly travel choices. Tourism stakeholders can develop more effective strategies to promote sustainable tourism by comprehending how Instagram travel influencers affect users' perceptions and decisions about travel destinations for sustainable tourism, as well as the influence of geo-location data on the users' selection of such destinations. Ultimately, the paper aims at contributing to the sustainability of the tourism industry, which is critical for preserving natural and cultural resources and for ensuring the long-term viability of the sector.
The paper continues with an extensive review of the relevant literature and the presentation of the research hypotheses and methodology. In the next two sections, the results of this study are highlighted, followed by the relevant discussion on them. The paper ends with the conclusions and the implications of the study, as well as the relative limitations and suggestions for further research.

Internationalization of Destinations and Inbound Tourism
In tourism, internationalization is often associated with product and destination competitiveness [23] and is considered a trigger factor for the formation of a destination's image and growth [24]. Territorial resources that support a region's economic dynamics, connections, and networks which allow tourists to reach the destination and facilitate their movements within it, as well as companies that transform a region's endogenous resources into tourist products, appear to be crucial elements that contribute to the internationalization of a destination [25]. Moreover, internationalization is aligned with the concept of territorial economic development that values quality, innovation, identity, and differentiation by focusing on the attractiveness of inbound tourism rather than domestic [26].
Inbound tourism, i.e., tourism coming from abroad into a country, represents a significant revenue source on a country level and constitutes an important activity in the exportation category, creating a high source of business activity, income, employment, and foreign exchange for the local markets [23,26]. The significance of international inbound ("foreign") tourism has been fully highlighted for its economic importance in tourism destination areas [24]. By eliminating the barrier of distance, inbound tourism benefits the destination, as it brings many benefits and resources into a developing or less developed country [25]. As a result, Buhalis [27] states that inbound tourism is highly linked with the internationalization of destinations, where the mobility of tourists creates links beyond borders. In the same research, a key conclusion refers to the tourism-growth relationship [27], concluding that less developed countries are more likely to benefit from international/inbound tourism [27,28].

Sustainability and Tourism Destinations
A destination's internationalization is important as it creates opportunities for foreign income flows to the destination's economy, as well as information and knowledge sharing, improvements of the destination's reputation, low dependency on domestic tourism sources, and high levels of overall sustainability [29]. Glyptou et al. [17] proceed to a cluster analysis of performance rankings of Mediterranean destinations, concluding that sustain-able destinations are characterized by high economic and social performance combined with a low environmental footprint.
However, maintaining and enhancing a sustainable destination's image in international markets is a challenging task [30]. Romao et al. [31] build their research based on structural analysis regarding the motivation and satisfaction of global tourists from different nations and cultures, stating that there is an opportunity to attract long-haul visitors who spend more and behave sustainably to destinations; this is even more important when domestic tourists cannot support the development of a destination [32]. A sustainable tourism destination considers assuring the ecological or environmental impact [33]. This means that, among other things, it should take care of the environmental resources for achieving high levels of positive impact on society, nature, and visitors, and, simultaneously, maintain the cultural sustainability of the destination and its overall brand image awareness [34,35].
A high percentage of destinations still present limited brand awareness in terms of quality among potential tourists [36] who use the internet as their key source of information [37]. Social media platforms can contribute to a traveler's awareness process of different destinations [38]. Through their rapid level of penetration, low-cost results, and global reach, these platforms comprise one of the main tools of a destination marketing strategy [39]. Therefore, the relationship between social media and destination marketing is highly interrelated [40]. Contemporary destinations seek increased brand awareness through users'/travelers' social media engagement [41].

Social Media, Parasocial Interaction, and Influence
According to the literature, direct communicating, engaging, and sharing are the main three characteristics of social media that contribute to shaping travelers' perceptions on a destination's image formation [42,43]. With shared experiences on social media constantly increasing, consultation before and during the trip, as well as consideration of content generated by other travelers (as influencers) gaining high importance [44], engagement through digital platforms and social media influencers has become a significant component of the internationalization of tourism destinations [45]. Social media has transformed users from being passive recipients of marketing messages to being communicators who can openly share their opinions regarding products, services, or destinations [46,47]. Being this type of communicator has created the term "influencer".
Several researchers stress the role and importance of these influencers in social media communication. For example, Menge [48] points out that they are characterized by the key elements of the general theory of power, namely (1) the ability to use force digitally, (2) the accessibility to digital resources, and (3) the collective acceptance from several groups of social media users globally. Vrontis et al. [49] highlight the emerging trend of social media content creators, known as social media influencers (SMIs), and the power generated by them as a main source of information for their audience. Nowadays, influencers play an important role in international social media marketing strategies [22]. Shan et al. [50] emphasize the endorser/promoter's impact on influencer marketing, underlining the role of parasocial interaction in the influencer and users' relationship. In more detail, Kim's study [15] tries to analyze the theory of parasocial interaction by examining users' illusionary and interactive relationships with media personas under the scope of viewership's influence, concluding that users tend to present higher interaction with their media personas when they are closer to their everyday life. Lee et al. [51] conclude that the role of parasocial interaction in influencer marketing is significant in the followers' active engagement and the creation of strong relationships with influencers, who are perceived as relatable and intimate figures in recommending products or destinations.

Instagram and Influencers
Instagram has proven to be the most popular social media platform presenting a high level of engagement in terms of content shared, while it also exists as the most preferable resource for inspiration and information [1]. Instagram was chosen by Breves [9] due to its large advertising revenue and its effectiveness as a platform for testing the relationship between followers and social media influencers during advertising campaigns. Socialmedia-based interaction has created a vital shift in connectivity between products, services, and users.
As users love visual content, Tariq examines user-generated content on Instagram under two major types of information [52]: (a) geographic and temporal information, and (b) the visual content of the photo or video that provides valuable sources for generating insights, where he concludes that geographic information has a key role of post promotion.
Backaler [53] describes that Instagram travel influencers could even be characterized as representatives of destinations, in the sense that they shape travelers' decisions to choose a destination while presenting a place [53]. By proceeding to a cross-factor analysis, he concludes that the number of followers, the behavior towards the influencer's audience, and the engagement under posts comprise key factors in evaluating the power of travel influencers for shaping audience attitudes [53]. If they present a high level of influence, they create a win-win strategy for tourism brands as virtual brand ambassadors in the era of destination marketing [54].
Ingrassia et al. [55] use netnographic analysis combined with the AGIL model approach (Adaption, Goal attainment, Integration, and Latent pattern maintenance) to measure the power of Chiara Ferragni's-one of the most famous Instagram influencersactivity and communication via her Instagram profile on promoting Italian tourist destinations worldwide to her loyal followers.
The loyalty of users is also crucial [56], and many individuals tend to become increasingly interested in the tourist community by reading personal travel evaluations and following Instagram influencers who promote sustainable tourism [6]. This indirect influence seems to accelerate the decision-making process by the followers, as it creates the willingness to choose the same destination [57].

Instagram Travel Influencers and Location-Based Social Media Data
The rise of influencer marketing as a cost-effective and high expansion results tactic of marketing has created new types of influencers in the tourism sector, such as Instagram travel influencers [58]. The selection of destinations can be differently associated with the group of tourists due to the different preferences of people influenced by their country of origin [59]. There have been many attempts to analyze travel behavior and location selection in a way that takes into consideration tourists' preferences, as well as their influences from travel opinion leaders through social networking sites [60].
Vu et al. [61], introduce new data sources derived from user-generated content -called location-based social media data-tested under the spectrum of influential and destination marketing. These sources are derived by location-based social networks (LBSNs), where the connections and interactions between users are based on creating virtual data that are connected to a specific location [7,20]. Li [59] moves a step forward and tries to examine the contribution of geo-location data, as presented by celebrity influencers' posts, on the multi-day and multi-stay travel planning of users. The above two studies conclude that location-based social media data, when presented by influencers, are key drivers for the users' selection of a destination [59,61].
With the advancement of the Global Positioning System (GPS) technology, geographical information can be stored in so-called geo-tagged photos [7]. The geographic and temporal information make influencer-generated posts an interesting source for the study of tourism destinations and the tourists' decision-making process [54]. Chen et al. [62] study location-based social networking platforms with the use of GPS and new marketing tools (usually referred to as check-in or geo-tag recommendations), concluding that these tools provide people with the ability to share their locations among their social communities when they decide to share their geo-location information. Vassakis et al. [63] examine the tourism recommendation system using geo-tagged photos and social platforms' Ap-plication Programming Interface (API) without considering the role of the influencer's parasocial ability during the posting process, presenting a partial point of view regarding the influence of geo-location data on users' engagement.
Besides static posts containing normal text, hashtag(s), and/or check-in data, referring to the location of Instagram stories is a common practice used in the promotion of tourism destinations by travel influencers [20]. An Instagram influencer's location history consists of (a) the rating history (e.g., per visited location) and (b) the check-in history followed by the related check-in location/geo-tag and geo-location hashtag [64]. When it comes to geo-tags/hashtags, the English language is generally used by Instagram travel influencers for boosting visibility and approaching more multilingual users [18,65].

Hypotheses Formation
Inbound tourism has an important impact on regional competitiveness and the overall sustainability of tourist destinations on a global level. The process of planning a journey is dominated by digital tools as well as by travelers'/users' posts or opinions, and tourist destinations are competing to attract inbound tourists [66]. As a result of the intensive use of social media, destination marketing has reformatted its communication strategy by putting the emphasis on digital and social media platforms [41].
In this context, a growing interest in social media influencers as drivers in the decisionmaking process of users for sustainable destinations has been recorded [25]. Studies suggest that users proceed more easily in engaging with everyday influencers rather than celebrity influencers, as users consider them to be more relatable and trustworthy figures [56,57]. Other studies [67,68] state that when trust between influencers and users is developing through strong parasocial interaction in social media platforms, the support of the destination's brand awareness is increasing.
The identification of motives and influences on the selection process of a location is considered a starting point for inbound tourism attractiveness [60]. The nature of images/posts on Instagram benefits sustainable tourism destinations with new tools for their marketing strategies [67]. At the same time, higher levels of digital and parasocial engagement on Instagram help in identifying and reaching new potential visitors [1]. According to theory, when an individual sees that a "product" is receiving a high-level of engagement from peers and groups of influence, he/she starts to develop the same perception of "product" quality [58]. Through the content generated on Instagram, digital influencers, in general, have the ability to formulate their followers' perceptions and attitudes during their decision-making process [69]. According to Zang et al. [54] and Kim [15], high levels of parasocial interaction play an important role in the relationship between an influencer and his/her followers, suggesting that users can even proceed to additive consumption after consulting influencers' recommendations and posts. This could also be assumed when Instagram travel influencers act as brand advocators or experts for a tourism destination [66]. As a result, the first hypothesis of this research is formed as follows: H1: Instagram travel influencers constitute key drivers on users' selection of sustainable tourism destinations.
In tourism literature, social media and influencers' content, including geo-tagged travel content and hashtags on posts, have dominated as additional travel data sources for the estimation of travel demand [39]. It is considered that these location-based data provide high-quality information from a marketing perspective [70]. Furthermore, users tend to be more associated with an event or location of a presented destination when geo-location data are used through social media, especially through Instagram [16], for boosting a destination's brand image [35]. Digital influencers usually describe geo-location data (i.e., geo-tags and geo-hashtags) as important types of information in a post that inspire their audience, reach new viewers, and gain more engagement [71,72]. Thus, the second hypothesis of the research is stated as: H2: Geo-location data used by Instagram travel influencers have a moderating role in users' selection of sustainable tourism destinations.

Methodology
This paper tries to stress the role of Instagram travel influencers in shaping users' opinions of a sustainable destination as well as the relation of geo-location data used by them to facilitate the users' selection of such a destination. Therefore, it focuses on investigating two main relationships. As highlighted in Table 1, the first one is between Instagram travel influencers-the independent variable-and the users'/travelers' selection of sustainable tourism destinations-the dependent variable. The second relationship introduces the use of geo-location data as a moderator variable that might amplify the first relationship. A moderator variable affects the strength of the relationship between an independent and a dependent variable [73]. In research, in order to infer that a variable is a moderator variable, there must be a significant statistical interaction between the predictor and the moderator (i.e., p < 0.05) [74]. A moderator variable affects the relationship between a predictor variable (X) and an outcome variable (Y) [73,74]. Moderator variables affect the strength of the relationship between X and Y [73,74]. Moreover, as adapted from Naciye and Adem [2] and Kim's study [15], the research uses two control variables in order to prevent research biases that can affect its results. In this study, the two control variables refer to the individuals' average level of spending per visit, which consists of the necessary component of economic impact analysis for marketing and policy decisions [2], and the number of daily active Instagram users, as this is the factor that affects Instagram popularity every day in the world's social media ranking system [15].
Taking into consideration the scope of time allowed and the data availability, the examined period was 2017-2019. This period was chosen due to the high scores in tourism globally, before the disruptive influence of COVID-19 on traveling behavior [67,72]. The data collection is based on the selection of 30 sustainable tourism destinations/countries considering the number of inbound overnight tourists per destination to be more than 500,000 people [75][76][77].
Using the approach of the International Union for Conservation of Nature [66], these 30 selected countries/destinations are defined as sustainable due to their high socioeco-nomic performance and low environmental pressure footprint, presenting an overall score of more than 65% on the sustainable development index (65-75% as strong sustainability indicator, while 75-85% as very strong sustainability level) [78]. Moreover, based on Tran and Rudolf's recent research that spotted the majority of sustainable destinations to be concentrated firstly in Europe and Asia [79], 22 of this sample's sustainable destinations are in Europe (Finland, Denmark, Sweden, Norway, Austria, Germany, France, Switzerland, Ireland, Estonia, United Kingdom, Poland, Czech Republic, Latvia, Slovenia, Spain, Netherlands, Belgium, Portugal, Hungary) while the remaining eight are located in Asia (Japan, Republic of Korea, Singapore, New Zealand, Thailand, Vietnam, China) as presented in the Sustainable Development Report Rankings 2022 [77].
For selecting the sample of influencers for this study, several lists on social media and experts on tourism marketing studies were consulted to help in the identification of the most important global travel influencers. Thus, a list of 200 influencers was created through Influencer Marketing Hub platform, from which only those that presented the identification of traveling experts on their bio were selected. Instagram was chosen as the examined social media of this research because, according to Statista [13], it hosts 94% of the global share of influencer campaigns using social media platforms.
As a result, an ad hoc Instagram account was generated to follow the 200 influencers [79]. As a result, 10 popular macro-travel influencers-a new type of influencer specialized in traveling with 50,000-150,000 followers on Instagram, that present a level of engagement of more than eight and likes per post of more than 20,000-were selected to form the independent variable [79]. The selection of the macro-travel influencers was based on the recent findings by Statista [13], where Instagram alone accounts for over 500,000 active influencers with more than 15,000 followers, which constitutes 39% of all Instagram accounts. Among this group of active influencers, 81% have between 50,000 and 150,000 followers. Only Instagram travel macro-influencers with these characteristics were examined in this study. Moreover, as derived by Statista, Keyhole, and Tag finder official libraries, 30 sustainable destinations'/countries' geo-tags and geo-hashtags (#country/destination) that have appeared in more than five posts per influencer were used for measuring the moderator variable [80].
The design employed is the cross-sectional analysis, as data collection refers to a specific period and classification of data (date, number of likes, engagements, and tags per post) [81,82]. This type of analysis tries to answer "what" instead of "why", allowing researchers to form assumptions through hypotheses and test them using other research methods [82]. For this reason, quantitative research based on secondary data is combined here to support the testing process of the hypotheses [83]. For the examination of the hypotheses mentioned previously, a multiple hierarchical analysis using SPSS Statistics was implemented. This type of analysis consists of a valid way to examine and predict the impact of an independent variable on a dependent one [84]. A panel data model for organizing the data of the sample, as also used in Ergemen [81] and Pérez-Rodríguez et al.'s [84] research, and a regression model described by Pan and Dossu [85] were used to establish the relationship between location-based social media data and the selection of the sustainable tourism destinations [72,84].
The Yit = α + sitδ + zitβ + εit (1) equation tries to test the relationship between the Instagram travel influencers' power and the selection of a sustainable tourism destination by the users. Y corresponds to the destination's selection using the number of inbound tourists as a measure, combined with the i and t subscripts, which refer to the country and the exact year, respectively [86]. Next, α is the constant, s represents the independent variable (travel influencers' power), and "the coefficient δ is added to consider the effect of the independent variable on the dependent variable" ([84], p. 22; [86], p. 27). Finally, z refers to the control variables (the individuals' average spending and the number of active social media users) while regression's error is represented by the ε [82].
The equation introduces the moderating effect on the tested relationship between the independent and the dependent variable. The moderating effect, represented by e, is the direct effect of geo-location data on the sustainable destination's selection, and eitsit denotes the moderating impact of geo-location data on the independent variable, while the other variables do not change as presented through the first equation above [83,86]. Table 2 presents the analysis of the descriptive statistics of the examined variables. In this table, normality is not satisfied due to the fact that Skewness and Kurtosis are greater than ±1 for the 4 out of 5 variables showing that the data for those variables are not normally distributed. Thus, normalization of the examined variables was conducted. Table 3 presents the outcome of normalization. Table 4 shows the means, standard deviations, and correlations of the tested variables, while Table 5 shows the regression and moderation findings used by the SPSS output.   Statistical significance: + p < 0.10, ** p < 0.01, *** p < 0.001.

Results
The first four variables in Table 3-namely, Instagram travel influencers, Users' selection of sustainable tourism destinations, Country's geo-location data, and Individuals' average level of spending per visit-have a normal distribution with Skewness and Kurtosis falling within the ±1 range for normality. Although the variable of Daily active Instagram users is slightly greater than the valid value of ±1, it is accepted because it is a control variable and has no significant effect on the subsequent steps of data analysis in SPSS. Furthermore, the sample of the first 120 observations was reduced for two reasons: (i) in Table 2, the variable of Instagram travel influencers had 10 missing observations of data, and (ii) in Table 3, the extreme values had been removed after data normalization in the final testing sample of 90 observations. Table 4 displays the means, standard deviations, and correlations of the tested variables, while Table 5 highlights the results of the regression and moderation analysis used in the SPSS Statistics. Table 4 shows the correlations between the variables investigated in the testing of the hypotheses. The users' selection of sustainable destinations through the level of inbound tourism (dependent variable) is significantly and positively related to the Instagram travel influencers (independent variable) at a country level (r = 0.498, p < 0.01). The geo-location data are negatively related to the users' selection of sustainable destinations (measured through inbound tourists at a country level), having a small effect on the above relationship (r = −0.131, p < 0.05). Geo-location data have no impact on all the other variables under investigation.
The multiple hierarchical regression results for testing the users' selection of sustainable tourism destinations (measured as inbound tourists) at a country level is shown in Table 5. R 2 describes the percentage of each model in the variation of the dependent variable based on the entered variables. R should be as close as possible to 1 [83].
The control variables are included in Model 1. This model depicts the variables of Individuals' average level of spending per visit; the number of Daily active Instagram users were entered, while the users' selection of sustainable destinations (dependent variable) maintained its consistency in all four models. This model was statistically significant with F = 88.530, p < 0.001 and explained 72.5% of the variance in the selection of sustainable destinations. In other words, the two control variables influenced the users' selection on sustainable destinations at a country level with 72.5%, and the remaining 27.5% was influenced by other factors.
The variable of geo-location data entered into Model 2 examined the level of its influence on the dependent variable while all the control variables were kept constant. The model was statistically significant with F = 79.59, p< 0.001. The use of geo-location data by travel influencers explained a 72.9% variance in the users' selection of a sustainable tourism destination at a country level (R 2 Change = 0.003, F = 0.064, p < 0.10), while the control variables were unchanged.
The introduction of the independent variable (Instagram travel influencers) as well as its impact on the dependent variable are presented in Model 3. This model was also statistically significant with F = 86.154, p < 0.001 and it was able to explain the 82.4% of variance in the selection of a sustainable tourism destination by users at a country level.
The final model investigated the two hypotheses of the study while introducing the moderation effect. Presenting statistical significance (F = 82.020, p < 0.001), Model 4 made no additional contribution to the variance in the users' choice of a sustainable tourism destination and exhibited a zero change in R square. Furthermore, it was obvious from this model that the Instagram travel influencers affected the selection of a sustainable tourism destination (β = 0.532, p < 0.01).
This result leads to the acceptance of H1, i.e., there is a positive relationship between Instagram travel influencers and the selection of a sustainable tourism destination by users. However, the other results indicate that there is no significant relationship between Instagram travel influencers at a country level and the selection of a sustainable destination when this relationship is moderated by the geo-location data used by the travel influencers when presenting a country's destination on their posts (β = −0.037, p = 0.464). Therefore, H2 is rejected since there is no proof for a negative or positive impact of the moderator on the relationship between the independent and the dependent variables.

Discussion and Implications
Instagram is widely used as a key platform for destination brand image presentations, and it is becoming increasingly important in sustainable tourism [86]. The findings of this study illustrate the significance of influencer marketing through Instagram for the attractiveness of sustainable inbound tourism. Furthermore, the findings provide key knowledge for sustainable tourism destinations regarding their brand image promotion through social media influencers and geo-location data, a scientific area with growing academic interest [87].
The significant power of social media platforms as sources of travel information makes users more attached to Instagram travel influencers that can consist of strategic elements during the decision-making process regarding their travel and choice of sustainable destinations [67]. This article addresses two of the main topics in influencer and destination marketing of sustainable destinations: the identification of the power of the macro-Instagram travel influencers on the users' decision-making process under the scope of parasocial relation theory and the evaluation of geo-location data as moderators between the relationship of Instagram macro-travel influencers and users.
As Instagram tends to present higher engagement, interaction, and content-generation rates than other platforms, the rise of the Instagram macro-travel influencers has created new virtual opinion leaders, different from the well-known celebrity influencers, as they are more relatable to their audiences, whereby helping them to form tourists' decisions worldwide [1]. Counting by the number of inbound tourists, the role of the macro-travel influencers seemed to contribute highly to the overall selection process of a sustainable destination due to the high parasocial relations that existed between users and influencers [53]. In addition, according to the findings of the study, the use of Instagram's popular macro-travel influencers could be a strategic tool for boosting the brand image and overall attractiveness of sustainable destinations, as well as achieving high engagement, especially when the influencers use the same tone of voice with their followers [56].
Nevertheless, geo-location data such as geo-tags and geo-hashtags in the Instagram macro-travel influencers' posts were not represented by the results as moderating factors for the selection of sustainable destinations by travelers. Even though geo-tags and geohashtags are types of information often used by influencers to characterize their posts through locations and to expand their global awareness, it seems that additional variables may need to be tested for supporting the moderating effect. The findings showed that it would be more efficient for the promotion of a sustainable tourism destination on Instagram to be combined with additional information besides geo-location data used by the Instagram macro-travel influencers. Furthermore, geo-location data combined with other influential factors, such as co-branded methods employed by local firms and NGOs, could boost the internationalization of a destination's brand [88], an area that needs further investigation for sustainable tourism destinations. Finally, the aspects of the country's competitiveness in the sphere of tourism are bound to the attractiveness of the destination, the successful functioning of the tourist business on the international market, and the overall sustainable performance of destinations [32].

Theoretical Implications
It is a fact that there are many studies which show how social media influencers exert a positive impact on consumers' purchase intentions, e.g., [89,90], and how their endorsements have been found to increase favorable attitudes, intentions, and behaviors towards organizations [91,92]. Much research has also examined the impact of social media influencers on the selection of a tourism destination, e.g., [53][54][55][56][57][58][59][60][61][62][63][64][65][66][67]93]. The findings of this study essentially reaffirm the results of the previous studies and expand on the existing social media influencer theory by illustrating the significance of influencer marketing through Instagram for the attractiveness of tourism destinations that can be characterized as sustainable.
The present research focuses on Instagram, which is the influencers' most favored media platform [1,94]. However, this study could be the trigger for research that examines travel influencers on other media platforms, such as LinkedIn, TikTok, or YouTube. Moreover, it could be the springboard to study the motives of the travel influencers' choices or the content of travel influencers' posts and its impact on less popular or unknown sustainable tourism destinations. Finally, it would be interesting to find out the travel influencers' choices for alternative sustainable tourism destinations.
Another theoretical implication of this study is that it enhances the existing literature regarding the role of geo-location data in Instagram travel influencers' posts for sustainable destinations. A few studies have already been conducted, concluding that geo-location data constitute a key facilitator for users in order to select a tourism destination [59,61]. However, the results of the present study are not in line with the findings of the previous studies. This study shows that the geo-location data uploaded by Instagram travel influencers do not significantly enhance the choice of sustainable tourism destinations by users. This seems to be an interesting finding that raises concern about the importance of geo-location data as a means of attracting tourists. According to the authors' opinion, there is no obvious explanation for this and it requires further investigation. The present research could also be a stimulus to study the combination of geo-location data with other information that could affect the choice of a destination since the content of information posted by travel influencers that positively influences users' decisions in choosing destinations remains vague [18].

Practical Implications
Concerning its practical implication, this study offers useful considerations for both Instagram travel influencers and marketers. Instagram travel influencers should aim at creating high parasocial interactions. This seems to strengthen their position as influencers and increases their negotiating power in case of their recruitment by companies or those in charge of promoting tourist destinations. However, the research showed that the posts of geo-location data do not enhance the choice of the travelers who follow them. Therefore, influencers may add additional information or choose other content that would make their posts more tempting. This is something that could be studied further in future research.
Instagram travel influencers can also draw attention to places that have taken steps to be more sustainable, including hotels and resorts that have adopted eco-friendly practices or places that have reduced their carbon impact. Instagram macro-travel influencers can persuade their followers to travel to these locations and promote sustainable tourism. They frequently highlight eco-friendly vacation spots and draw attention to the initiatives taken by local communities to protect the environment and promote eco-friendly travel. By sharing pictures, videos, and stories of sustainable destinations, highlighting eco-friendly activities, and discussing the importance of responsible tourism, they can inspire their followers to adopt more sustainable travel habits and make more sustainable choices when planning their trips. They can also spread knowledge on the significance of appropriate travel habits, such as minimizing trash and protecting the environment.
Moreover, Instagram travel influencers can inform their followers on how tourism affects the environment and local communities and educate them. They can encourage their followers to reduce their environmental footprint by suggesting eco-friendly activities, such as taking public transit or limiting plastic waste, and inspire them to lessen their environmental impact. By leveraging their influence on Instagram, they can help to protect and preserve the world's natural and cultural resources for future generations.
Marketers of sustainable tourism destinations could also benefit from the study's findings since Instagram is widely used for many destination marketing campaigns [79]. They could identify Instagram travel influencers with high parasocial interactions able to reach specific audiences in order to promote a sustainable destination, boost its brand image, and increase its inbound tourism. They could also cooperate with influencers to highlight a sustainable destination's important tourist landmarks, promote a specific destination's culture, or differentiate it from competing destinations, making it more attractive by leveraging a highly influential medium such as Instagram. Future research that would focus on the content of information that influences travelers could help marketers to work more effectively with influencers in order to promote more effectively and increase the attractiveness of a sustainable tourism destination through social media.

Conclusions, Limitations, and Directions for Future Research
The social dynamic of social media, such as Instagram, allows digital influencers to become generators of travel content and a destination's overall image [95,96]. Many travelers become interested in a destination by following bloggers or social media influencers and reading their personal travel evaluations, reviews, or other sorts of information, such as travel photos, stories, and hashtags that are often created and shared among virtual user communities globally [34,97]. Social media platforms have become essential tools for users in the decision-making process, helping them to select which destination to visit [34]. The interactive nature [53], user-generated content, and growing number of influencers on these platforms could create strong relations among users and enhance the attractiveness of a tourism destinations [68].
This paper discusses the impact of Instagram travel influencers and their posts of geo-location data on the selection process of exclusively sustainable tourism destinations. Its purpose is to examine (a) the role of Instagram travel influencers in shaping users' opinions of a sustainable destination and (b) the importance of geo-location data used by them to the users' selection of such a destination. The sustainability of tourism destinations refers to the improvement and maintenance of the natural resources and landscapes, as well as to the development of less mass-tourism behavior with respect to the destination's overall identity [34]. The research findings show that Instagram travel influencers seem to be one of the drivers in forming users' points of view for destinations and that they contribute to the overall selection process of sustainable destinations. In addition, the findings reveal that geo-location data used by Instagram travel influencers do not enhance the users' selection of sustainable tourism destinations.
A possible limitation of the present research is that it focuses solely on Instagram; other social networking sites are not examined. It is also concentrated on the period 2017-2019, as the period after 2020 is characterized by the COVID-19 stop/low level of travel in general. Additionally, it investigates the impact but not the process of influence of the Instagram travel influencers or geo-location data. This study is also limited in geo-location data and does not explore the content of travel influencers' posts or the impact of combinations of relative information on travelers' decisions. Finally, it does not examine less popular, unknown, or alternative sustainable tourism destinations or different groups of users or travelers.
Future similar studies could be conducted to examine other social media platforms, such as YouTube or TikTok, as well as other digital tools, e.g., blogging, search engine optimization, or mobile applications, allowing even comparisons between them. The same study could also be run in the after COVID-19 era to discover possible connections between the two periods. Future research could also investigate the impact of the examined data at every stage of the users' decision-making process in terms of selecting a sustainable destination, i.e., information search, evaluation, and purchase [5], or the impact of different types of inbound tourists, such as dark, heritage, mass, or culture tourists [88], different generations of tourists (e.g., X, Y, or Z generation), and different stakeholders, as well as different types of influencers according to their level of attractiveness (e.g., celebrity/mega influencers) or level of trust and authenticity (micro-influencers/nano-influencers) [4]. Furthermore, future research could explore the process of influence of the Instagram travel influencers or the content of travel influencers' posts and its impact on travelers' decisions for sustainable destinations, as well as different types of sustainable destinations, e.g., the less known or alternative ones.