Fostering Voluntourism Satisfaction and Future Behaviour in Island Destinations

: Volunteer tourism, which is commonly referred to as voluntourism, is currently a dynamic alternative travel option with a focus on sustainable tourism. However, existing literature reveals that voluntourism activities do not meet tourists’ expectation, fail to provide experiences related to environmental issues, and thus, leads to their dissatisfaction. Realising the importance of the satisfaction of the voluntourists’ future behaviour, applying the volunteer function inventory, coupled with environmental concern, the authors aim to identify factors inﬂuencing voluntourists’ satisfaction and present the outcomes of voluntourists’ satisfaction among island visitors in Malaysia. Using a purposive sampling method, the data were collected through a survey among voluntarists in east coast island tourist destinations. A total of 278 valid questionnaires were gathered from two sessions of data collection process. Due to the model’s complexity, SEM-PLS version 3.3.2. was employed to analyse the hypotheses of the study. The results of the study revealed that career and social functions, in contrast with other variables, do not positively inﬂuence the voluntourists’ satisfaction. The continuous intention and the intention to recommend factors positively support the research model. Studies on voluntourists in Malaysian island destinations are relatively novel. Besides enriching the literature on voluntourism, which is particularly scarce especially in the Asian setting, the ﬁndings are also beneﬁcial to local governments and voluntourism organisations to develop suitable approaches and policies to promote voluntourism in island destinations. The study is limited to the island destination setting. Future studies should focus on other destinations such as cultural and heritage sites, because these destinations have sentimental values that should be preserved.


Introduction
In the 21st century, the tourism industry experienced an expansion [1] and increased prominence of what is known as volunteer-oriented tourism. Volunteer tourism, which is more often referred to as voluntourism, is currently a dynamic alternative travel option with a focus on sustainable tourism [2,3]. Offering experiences free from commodification, voluntourism shifts the tourism paradigm away from mercantilism by placing a focus on ecological, cultural and social values and by benefitting local communities and the environment [4]. The act of volunteering may be defined as providing one's time without expecting a monetary return [5]. Voluntourism is widely discussed as an upcoming subcategory of mainstream tourism and host communities [4,[6][7][8][9]. Indeed, this optimism is spurred by the increasing number of tourists embarking on such activities, and its popularity may signify a worthy development in the tourism industry [10]. Voluntourism activities in the island destination context are purposely designed for the sustainability of destinations that triangle between economy, culture, and environment, also known as the sustainability trinity [11]. It is seen as an important indicator for successful tourism development because it stresses the comprehensive betterment of society and ensures the industry's continual growth in the long term. In the context of volunteer tourism, the three pillars in the trinity can be strengthened with the input of care from international volunteers and residents. Care is not only a moral value, it is also a practice in everyday life [12]. In general, research on sustainability has been widely discussed in various fields such as the smart city concept [13], green hotels [14], and in the tourism research context with research on cultural heritage [15], spatial destination [16], and residents' perception [17]. These fields have become highly attractive among researchers who explore and present new findings. Overall, the discussion on sustainability is important for the benefits of the economy, the culture, and the environment of the destination from a tourism perspective.
Brown and Morrison [6] argue that "tourism often leads to the exploitation of host communities, their cultures, and environments"; others posit that the volunteering aspect of voluntourism offers an added value to tourism, an economic sector which is plagued by negative aspects of capitalist consumerism [4]. In the literature, tourists from first world countries are more and more attracted to different travel opportunities that offer rich experiences and sustainable development at the point of arrival [18]. This links the requirements of both present and future generations without compromise [19].
The literature also explains that volunteers can be categorised into the two categories of organised and spontaneous volunteers. From a tourism perspective, island volunteer tourists associated with the organised volunteer category usually pre-plan their tour and activities at their preferred destination. They search for information about such activities through the internet, organisations, word of mouth and other tourists' experiences shared on websites. Subsequently, they plan their journey to the destination and follow a tour. However, under specific conditions, tourists may spontaneously become volunteers in instances where events or festival are organised where they willingly participate to gain experience. Alternatively, some tourists may voluntarily take part in natural disaster relief during their vacation to help and assist the public during such tragedies. In general, volunteer tourism is considered as organised when there are pre-planned activities and a clear aim and purpose for the tour.
However, existing literature reveals that tourist activities do not meet their anticipations. Tourists become less motivated and reports cast doubts on the effectiveness of providing host communities with monetary income [8]. In an example from Vietnam, voluntourists regretted that they had not gained experiences related to environmental issues and that the lack of direct contact with local communities resulted in a sense of dissatisfaction on their personal achievements [8]. Coghlan [20] also highlights that a discrepancy between the volunteers' expectations and their real experiences could lead to reduced levels of satisfaction, volunteer motivation, and commitment. Furthermore, voluntourists consist of a diverse group of people with disparate backgrounds, skills and motivation who pursue a diverse range and types of experiences [21]. Meeting these groups of voluntourists' expectation and satisfaction is not an easy task. In the absence of satisfaction, voluntourists will hesitate to recommend voluntourism to their colleagues and potentially will not continue to be voluntourists in the future. Owing to the importance of satisfaction on the voluntourists' future behaviour, the authors identified the factors influencing voluntourism satisfaction and the effect of satisfaction towards their future behaviour. Additionally, the literature on voluntourism is predominantly based on the Western setting [22], which is dissimilar to the eastern culture, and thus challenging to justify and apply in the eastern region [23]. According to Nesa Ali and Rahman [22], there are a dearth of empirical studies conducted in the South East Asia region, focusing on voluntourists' continuance intention [24] particularly in the island destination setting.
The volunteer function inventory (VFI) model was employed to identify the role satisfaction plays on continuous tourist volunteers and on the intention to recommend this activity in an island tourism context as their main motivation to travel during vacations.
Although several studies investigate the VFI and satisfaction, there is little research on the relationship between these two [25], especially in voluntourism studies. The VFI has been tested in various areas of volunteering such as those involving the elderly, youth, sport events, expos, and libraries [26]. However, there are a lack of studies related to volunteerism where tourists become volunteers in the places they visit. Extending the VFI, the current study also adds environmental concerns because the study is limited to island destinations. As mentioned by Coren and Gray [8], some voluntourists are not satisfied with the inability to gain expected experiences in environmental voluntourism activities, thus signalling the importance of the environmental concerns among voluntourists. Furthermore, in the research setting on the island destinations, most of the voluntourism activities, such as beach cleaning and coral reef conservation, are related to the environment. This justifies why the authors decided to include the environmental concern as an extension to the VFI model. Moreover, the present study also addresses the effect of satisfaction on continuous behaviour of volunteerism because the enhancement of volunteer satisfaction and retention intention is a vital area to be studied [27]. There have been separate studies on volunteer motivation and satisfaction, but there is little research on the relationship between the two [25]. Therefore, by combining various factors measuring how satisfaction leads to intention, this article further discusses the impact of continuous intention among volunteers to continue their vacation activities.
By identifying the factors of voluntourism satisfaction, intention to recommend and continuance of voluntourism in a single model, the findings of the study not only contribute to the body of knowledge on voluntourism in the South East Asian setting which specially focuses on the island destinations, but is also beneficial to government agencies and voluntourism organisations to help them craft better approaches and policies. This will enhance voluntourists' satisfaction and their intention to recommend voluntourism to their colleagues, and at the same time incite them to continue their involvement as voluntourists.

Literature Review and Hypothesis Development
Satisfaction is closely related to motivation, which could lead to future behaviour such as continuing the activities or recommending them to others [28][29][30][31] and the ability to "discover oneself" through volunteering [25]. Studies on satisfaction rely on theories commonly used in other studies, such as the self-determination theory (SDT) by Deci and Ryan [32] or the expectation-confirmation theory from Oliver [33], which are commonly used in satisfaction studies in various contexts. The current study focusses on volunteers; therefore, the authors selected the volunteer functions inventory (VFI) developed by Clary et al. [34]. The VFI measures six underlying functions: (1) values, (2) social, (3) enhancement, (4) understanding, (5) protective and (6) career. The VFI was heavily criticised for its improper validation in volunteer research [35], however the VFI is still a popular choice among researchers studying volunteers' motivation in multiple setting such as sporting events [36], the elderly, faith based [27], non-profit organisations [37], hospitals, librarians [26], adolescents [38], and donators [39]. This corroborates with Clary et al.'s [34] findings on the generic relevance and number of functions in measuring satisfaction among volunteers in various contexts of volunteerism. Although volunteers engage in similar activities, their psychological functions may differ.

Career Function
According to Brockner, Senior and Welch [40], the career function refers to experiences that could be used for future careers based on volunteering activities. While taking part in volunteering activities, volunteers may gain specific experience which may be related to their current or future career. Hence, volunteering is not only helping others; it is also self-benefitting. Career has been found to have a positive relationship with satisfaction among volunteers [25,41]. Furthermore, the authors propose that: Hypothesis 1 (H1). The career function has a positive effect on satisfaction among voluntourists.

Enhancement Function
While performing activities, voluntourists gain an experience which can enhance their knowledge and understanding based on the activities in which they are involved. For the current study, voluntourists gained knowledge on environment issues, particularly those related to island destinations. According to the enhancement function, greater knowledge gained results in higher satisfaction. Being a volunteer could enhance an individual's self-esteem while preserving ego, and could lead to feeling good about oneself by helping others [42]. Previous studies by Johnson et al. [41,43] found that enhancement has a positive effect on the volunteers' satisfaction. Based on these findings, the authors propose that: Hypothesis 2 (H2). The enhancement function has a positive effect on satisfaction among voluntourists.

Protective Function
Protective function refers to when volunteering activities reduce negative feelings, such as guilt, or when they address personal problems [34]. Some volunteers may counter negative feelings such as guilt of past behaviour by volunteering [44]. Protective behaviours due to care or concern about certain things can lead to volunteering to protect what they enjoy. The protective function has been found to have a positive effect towards volunteers' satisfaction [43]. Hence, the authors propose that: Hypothesis 3 (H3). The protective function has a positive effect towards satisfaction among voluntourists.

Social Function
Social functions are commonly one of the main reasons why volunteers are involved in volunteering activities. Social function in volunteers refers to socialising with communities and the environment [45]. Voluntourism allows tourists to socialise among themselves and with local communities. This informal activity could create stronger and lasting relationships among participants. Volunteering activities also provide a platform for people to mix with strangers [46]. Through volunteering, volunteers can create new networks, trust, and cooperation. Engaging in new exchanges with people from different parts of the world through identical interests could delight voluntourists. Therefore, social function has been found to have a positive relationship with satisfaction among volunteers [41,43]. Thus, the authors propose that: Hypothesis 4 (H4). Social function has a positive effect on voluntourists' satisfaction.

Understanding Function
Through volunteerism, volunteers may gain experience by sensing new setting and opportunities to practice what is rarely used in an ordinary setting [34]. Different surroundings will provide new knowledge and understanding for volunteers. For this study, the focus on voluntourism in island destinations may surely enhance the understanding of the environment, especially the importance of preserving the island setting as a sustainable destination. The beauty of the untouched nature of the island is a lure for tourists to visit and revisit the destination. Engaging in voluntourism activities on the island will enhance the understanding of the environments among voluntourists. Prior studies reveal that there is a positive relationship between the understanding function and volunteers' satisfaction [41,43]. Hence:

Hypothesis 5 (H5).
The understanding function has a positive effect on voluntourists' satisfaction.

Value Function
Everyone has their own values. Volunteerism provides individuals with the means to express or behold important inner values which might be related to altruistic and humanitarian concerns. The literature provides a clear direction on the relationship between the value function and satisfaction. The value function, as established by Finkelstein [43] and Oh [26], has a positive relationship with satisfaction among volunteers. Accordingly, the authors propose that: Hypothesis 6 (H6). The value function has a positive effect on voluntourists' satisfaction.

Environmental Concern
Environmental concern refers to a belief, stance, and the degree of concern an individual holds towards the environment [47]. Environmental concern has also been described as the level of emotionality with which people are concerned with environmental issues [48]. The fact that voluntourists in the study were involved in beach cleaning activities justifies why this variable was included in the research model. Furthermore, environmental concern is regularly viewed as a crucial explanation for the extent to which one's behaviour is oriented by the notion of sustainability [49].
Most studies focus on the influence of environmental concerns on purchase behaviour in green studies. However, there are a lack of studies on the influence of environmental concern on satisfaction, especially in voluntourism studies. In the field of hospitality, it is common to view environmental concern as an indirect determinant of pro-environmental behaviour [50]. Environmental concern should be an essential element in studies related to environmental issues. Furthermore, [50] found that environmental concern has a positive relationship with satisfaction. Therefore, we postulate that: Hypothesis 7 (H7). Environmental concern has a positive influence on voluntourists' satisfaction.

Satisfaction Effect on Continuous Intention and Intention to Recommend
Satisfaction is a crucial component which has a vital effect on future behaviour. Satisfaction is always at the centre of marketing and tourism studies. As for volunteers, satisfaction refers to the relationship between the returns which are derived from volunteering activities and the personal sacrifice of volunteers [51]. In the current study, returns from voluntourism activities are cleaner beaches free from trash and debris. Meanwhile, sacrifice refers to the volunteers' time, money, and efforts. Volunteers rely heavily on their previous experiences to determine their future behaviours. Volunteers who feel that their purpose for joining volunteering programs were satisfactorily met will tend to associate again in the future.
The paramount satisfaction towards future behaviour such as continuous intention and recommendation is undeniable [52]. Previous studies [26,41,53] reveal that satisfaction is positively related to continuous volunteerism. On the other hand, there is a positive relationship between volunteers' satisfaction and the intent to remain volunteers [54]. Satisfaction has a positive impact on a volunteer's intent to recommend the organisation to other volunteers [54]. Individuals tend to recommend when they have had a favourable experience and when they are satisfied with their experiences during the activities [39]. Prior studies [55,56] confirmed that satisfaction has a positive relationship with the intention to recommend. Hence, the authors propose that the outcome of: Hypothesis 8 (H8). Satisfaction has a positive effect on the continuation of being a voluntourist.

Hypothesis 9 (H9).
Satisfaction has a positive effect on the intention to recommend being a voluntourist.

Materials and Methods
Data were collected among voluntourists at three island destinations on the east coast of Malaysia. The islands of Kapas, Tioman and Perhentian were chosen because the destinations continuously promote volunteer programs to tourists visiting the islands. Furthermore, there are volunteer centres in these locations such as the Juara Turtle Project, the Rumah Hijau at Tioman, and Ecoteer, Bubbles Turtle and Reef conservation on Perhentian island. The study focusses on tourists who have experienced volunteering activities related to environmental aspects, such as beach cleaning or coral reef conservation in those islands. Hence, a purposive sampling method was employed. Furthermore, convenience sampling already suffices if the nature of the study is to explore the veracity of a theoretical effect [57,58].
Due to the closure of these islands from October to December, as a result of the monsoon season, data were collected from January to March 2019. By employing a survey design, a questionnaire was distributed and self-administered. The data collection was conducted when voluntourists dined together and during sharing sessions on voluntourism activities at the centres. These moments were selected because respondents were more available to complete the questionnaire at these times. Although more than 200 voluntourists were approached, the authors only managed to identify 121 respondents who met the selection criteria. Voluntourists in other areas such as hotel services were selected. From 121 respondents, 2 were discarded due to straight line answers. Out of 119 respondents, 37 respondents were on Kapas island, 48 on Perhentian island, and 34 on Tioman island.
A small sample size is always an issue for survey studies. To increase the number of respondents, the researchers left some questionnaires with the person in charge on those islands. The researchers also briefed the person in charge on the study's voluntary nature and on the probability that volunteers may refuse to participate. A total of 187 questionnaires were collected within 3 months. Out of 187 returned, 28 questionnaires were discarded due to poor data quality such as when respondents answered in a straight-line way. Due to the use of dual data sources, a t-test was conducted to ensure that there were no significant differences between these two datasets. The result shows that there were no statistical differences between the two datasets; hence, they could be combined for further analysis of the study.
From a total of 278 respondents, 27.3% were on Kapas island, 40.7% on Perhentian island and 32% on Tioman island. The majority of the respondents (48.6%) were in the 18-25-year-old age bracket. In the sample, 58.3% were male, 64.4% were local tourists, 53.6% had a bachelor's degree as their minimum qualification, 62.6% had experience as a voluntourist for less than 1 year, and 85.6% of them were still single.
As proposed by Hair, Risher, Sarstedt and Ringle [59], to determine the minimum sample size, the study should rely on the power analysis which is based on the model structure. For the research model, the highest predictor of the model is seven, which points at continuing with voluntourism. As suggested by Gefen et al. [60], the study should use the power of 0.8 for a medium effect size. Following Green's [61] table, with seven predictors from the research framework, for a medium effect size as suggested by Gefen et al. [60], the minimum sample size is 103. The number of respondents of the study was 278, thus confirming that the sample size of the study was sufficient to test the hypotheses developed in the research framework.
All items were adopted from the established literature in the area of studies. The exogenous variable representing the VFI factors was borrowed from the original source by Clary et al. [34]. A five-item scale was used to measure the volunteers' motivations. Responses ranged from 1 (strong disagreement) to 5 (strong agreement) for environmental concern [62]. To measure the endogenous variable, satisfaction [34], the intention to recommend [63] and the continuing behaviour of voluntourism, the authors adopted the instrument from Venkatesh, Brown and Hoehle [64]. The responses ranged from 1 to 7 to avoid the common method variance as proposed by MacKenzie and Podsakoff [65] and Ngah, Gabarre, Eneizan and Asri [66].

Results
The authors employed smart partial least squares (Smart PLS) modelling due to the study's inclusion in the exploratory mode, because the study included a new variable (environmental concern) with the VFI, and due to the model's complexity. Based on Hair, Hollingsworth, Randolph, and Chong's [67], a study is considered complex if it has more than seven variables. The model in the present study consisted of 10 variables, thus confirming that Smart PLS was appropriate. Furthermore, following suggestions from the literature [68][69][70], in the present study the multivariate skewness and kurtosis were assessed. The results revealed that the data did not have a multivariate normal distribution: Mardia's multivariate skewness (β = 62.045, p < 0.01) and Mardia's multivariate kurtosis (β = 227.049, p < 0.01). Smart PLS is appropriate for data which do not meet normality requirements.
The respondents of the study answered the exogenous and endogenous variables of the study at the same time; hence, common method bias (CMB) due to a single data source should be remedied [71]. In the study, the authors employed both procedural and statistical methods. For procedural, a different anchor scale was used to measure the exogenous (1-5) and endogenous (1-7) variables as proposed by Podsakoff, MacKenzie and Podsakoff [71]. For the statistical method, the authors employed the full collinearity test as introduced by Kock [72]. A variance inflation factor (VIF) value greater than or equal to 3.3 signals that the study suffers from a common method bias issue. The analysis shows that all VIF values were less than 3.3, thus suggesting that the study was free from the common method bias. Table 1 illustrates the results of the analysis. Note: CV, continue as voluntourist; Eh, enhancement; Env Con, environmental concern; ITR, intention to recommend; Satis, satisfaction; Ud, Understand.
As proposed by Anderson, Kellogg and Gerbing [73] and supported by Ngah, Zainuddin, and Thurasamy [74], the authors employed a two-step approach to confirm the measurement model, which first consisted of confirming the reliability and validity of the items, and then proceeded to the structural model for hypothesis testing. At the measurement model, two tables were developed which showed the convergent validity and the discriminant validity.
To establish the convergent validity, the authors followed guidelines established by Hair, Matthews, Matthews and Sarstedt [75], which examine the loading, the average variance extracted (AVE), and the composite reliability (CR). Convergent validity was tested to ensure that multiple items were able to measure the specific construct [76]. The threshold value for loading and AVE is 0.5, and 0.7 for the CR. All values representing the loadings, AVEs and CRs for each construct were greater than the threshold value, hence confirming that the convergent validity was confirmed in the present study. Table 2 shows the results for the loading, AVE, and CR for the study. Discriminant validity can be established if the hetero-trait mono-trait (HTMT) values are less than or equal to 0.9 [77]. Table 3 illustrates the HTMT values for all constructs in the study. All values were smaller than 0.9, thus confirming that the discriminant validity was established and confirming that respondents understood that there were ten distinct constructs in the study. Based on results for convergent validity and discriminant validity, the authors concluded that the measurement items were valid and reliable for the study to proceed to the structural model. For hypothesis testing, instead of reporting the path coefficients, the standard errors, t-values and p-values for the structural model using a 5000-sample re-sample bootstrapping procedure as proposed by Hair, Risher, Sarstedt and Ringle [63], the authors elected to follow Hahn and Ang's [78] viewpoint that p-values are not considered adequate criterion when testing the significance of a hypothesis. Hahn and Ang [78] suggested using a mixture of criterions which could include effect sizes, confidence intervals and p-values. Table 4 presents the criteria which the authors used to test the hypotheses that were proposed. There were seven hypotheses related to satisfaction; the R 2 value was 0.535, indicating that the seven variables explained 53.5% of the variance in satisfaction. From these seven hypotheses, five were found supported, while the rest were unsupported. Enhancement (β = 0.126, p < 0.01), protective function (β = 0.193, p < 0.01), understanding (β = 0.167, p < 0.05), value (β = 0.290, p < 0.01) and environmental concern (β = 0.234, p < 0.01) were all positively related to voluntourism satisfaction, thus supporting H2, H3, H5, H6 and H7. Meanwhile, for career (β = −0.045, p = 0.205) and social function (β = −0.074, p = 0.168), H1 and H2 were unsupported. For continuing voluntourism (β = 0.631, p < 0.01), R 2 was 0.398, which indicates that satisfaction explained 39.8% of the variance in continuing voluntourism. The intention to recommend voluntourism (β = 0.307, p < 0.01) had an R 2 value of 0.094, which indicated that satisfaction explains 9.4% of the variance in the intention to recommend. Satisfaction was found to have a positive relationship with both constructs, thus supporting H8 and H9 in the study.
To show the importance of the exogenous variables towards the endogenous variables, the authors reported the effect size as guided by Hahn and Ang [78]. The effect size was categorised as large (0.35), medium (0.15) and small (0.02). For satisfaction, all the relationships had a small effect size, with a value of 0.09 as the highest effect size for satisfaction. Satisfaction had a large effect size for continuing voluntourism (0.66) and a small effect size (0.1) for the intention to recommend. Table 4 and Figure 1 illustrate the results for the hypotheses testing of the study. Based on developments in Smart PLS, as introduced by Shmueli et al. [79], the authors chose to use PLS-Predict. This is a procedure based on a holdout sample generating case-level predictions for constructs or items using PLS-Predict with a 10-fold procedure checking for predictive relevance, instead of reporting the blindfolding procedure. Shmueli, Sarstedt, Hair, Cheah, Ting, Vaithilingam, and Ringle [80] suggest that if all the item differences (PLS-LM) are low then a strong predictive power is established. However, if all are high then the predictive relevance may not be confirmed. Furthermore, if the majority is low, then there is a moderate predictive power, but if the minority is low, then there is a low predictive power. Based on Table 5, all the errors of the PLS model were reported lower than the LM model, thus it is possible to conclude that the model had a strong predictive power.

Discussion
From a tourism industry perspective, the volunteer function index model (VFI) is considered as applicable and is a steadfast instrument to measure the voluntourists' satisfaction in island tourism destinations. Furthermore, it was applied to measure and predict the voluntourists' continuous intention and their intention to recommend voluntourism in the island's tourism context. It is widely accepted that the VFI may incite managers or service providers at the touristic destinations to restructure their volunteer programs in the island context. The findings of this study may also provide guidance and ideas to service providers in the tourism industry to evaluate their current volunteer programs in order to sustain future demand and prospect.
In this research context, nine hypotheses were tested. The results of the study revealed that seven hypotheses were supported, and two hypotheses were not supported. The seven other variables had a significant positive influence on the voluntourists' satisfaction in the island tourism destination context, thus supporting the findings from other published studies discussed earlier. These variables are the enhancement function, the protective function, the understanding function, the value function, and the environmental concern function. These had a positive relationship on voluntourists' satisfaction. These findings were found to be consistent with those from research in different contexts. These variables were found to significantly support the environmental, social, and economic elements in the island tourism context with which voluntourism is usually associated. There is little doubt that these variables contribute significantly to the present research context.
The findings on the enhancement function were aligned with those from Johnson et al. [41] and Finkelstein [43]. They show that joining the volunteers' activities in the island destination enhanced their experience and increased their knowledge and understanding of the environments in island destination. By taking part in activities during voluntourism events, voluntourists may see their tasks in a different perspective because the activities may be not related to their daily lives. Even though the tasks may be tiring, voluntourists gain meaningful experiences, providing them with a better understanding to perform assignments. This will enhance their knowledge and understanding of the importance to preserve our nature, especially in island destinations where tourists enjoy their vacation. Each activity provides different enhancements based on how much they learn and gain from the activities. Beach cleaning and coral preservation activities conducted in different settings result in different enhancements leading to the voluntourists' satisfaction. Furthermore, the majority of respondents had less than one year of experience; hence, activities such as beach cleaning and coral preservation enhanced their experience and knowledge in these respective areas. Moreover, the activities and scenarios at island destinations are completely different from those at non-island destinations.
Protective functions which relate to reducing feelings of guilt were found to have a positive effect on satisfaction. This finding is similar to those from Finkelstein [43]. Voluntourists may feel guilty towards the environment and the surroundings in island destinations. Although voluntourists might not contribute to environmental issues plaguing islands such as the huge amount of debris on beaches and coral bleaching, they may realise that this is caused by human behaviour, and their family or peers might contribute to the problem. Taking care of what is precious to volunteers could enhance their satisfaction. Satisfaction is also gained when these precious things are preserved and are in good condition. Beach cleaning and coral preservation support environmental sustainability in their own ways. Keeping the beaches clean sustains the beautiful scenery and promotes joyful feelings for tourists in that area. Preserving the coral is not only crucial to diving activities, but also ensure that the ocean's natural heritage is sustained. Hence, engaging in volunteer activities during vacations could curtail their guilt.
The understanding function was also found to have a positive effect on voluntourist satisfaction. This finding strengthens those from previous studies [41,43] where the same effect was found. Island destinations with beautiful beaches and crystal-clear water provide different surroundings from other locations, which contributes to new knowledge on the importance of caring for nature. Thus, to ensure voluntourist satisfaction, the event conducted should provide voluntourists with new knowledge and experience. This could be achieved by tour organisers who explain island phenomena during voluntourism activities. Real experiences during voluntourism activities provide voluntourists with a better understanding of what is happening to our environment. A deeper understanding of the human impact on the environment could result in higher satisfaction.
The value function was also found to have a positive effect on voluntourist satisfaction. Despite different human beliefs and values, all beliefs should support efforts for the betterment of destinations. This finding is aligned with those from Finkelstein [43] and Oh [26], thus confirming the importance of value in explaining the satisfaction of volunteers. If voluntourism activities have a positive value from the tourists' perspectives, the chances for them to be satisfied with the activities will be greater. Hence, organisers should not forget about value to ensure that tourists will be satisfied with volunteer activities. Enhancing an individual's value via voluntourism activities could produce great satisfaction. Furthermore, enhancing values with people from different parts of the world in a carefree manner could be a good reason why voluntourists are satisfied with voluntourism.
Environmental concern demonstrates the voluntourists' feelings towards the environment. The study revealed that environmental concern has a positive effect on satisfaction. This finding supports a previous study conducted by Zhang,Xiao and Zhou [50], who demonstrated that environmental concern has a positive relationship with satisfaction among Chinese consumers, thus confirming the role of environmental concern on satisfaction. This finding shows that tourists who visit the destination once in their life are still willing to join volunteer activities due to their strong connection with the environment. Thus, that is one of the reasons why tourists are satisfied with the voluntourist activities although the activities are energy-and time-consuming. Enjoying a good environment at island destinations is one of the reasons tourists visit them. Hence, owing to that reason, voluntourists have a great time vacationing while at the same time their concern about the environment provides enormous satisfaction.
Satisfaction with the voluntourist activities was found to have a positive effect on the continuous intention of being a voluntourist in the future. This finding echoes previous studies [26,41,81], which reveals that satisfaction is positively related to continuous volunteerism. This finding also endorses the influence of satisfaction on the continuous behaviour of volunteerism. Hence, in order to appeal to current voluntourists to enhance their voluntourism behaviour in the future, satisfaction of participants in voluntourist activities must be prioritised. Efforts from event organisers on Perhentian and Tioman islands, who organise dining events at night should be pursued. Instead of offering a sharing session, dining sessions could also act as a planning platform for future activities.
The study also revealed the positive effect of satisfaction on the intention to recommend. This finding is corroborated by previous studies [55,56] which confirms that satisfaction has a positive relationship with the intention to recommend, thus demonstrating the cruciality of satisfaction on the recommendation behaviour. When voluntourists are happy and satisfied, they share their experiences with others and encourage colleagues and relatives to follow their path. A photography session and the sharing of activities on social media such as Twitter, Facebook and Instagram are viewed as a soft form of recommendation by voluntourists to their relatives. Sharing a delightful and joyful moment during voluntourism activities creates a stronger appeal, because a picture is worth a thousand words.
The career function and social function were found to have an unsupported relationship with voluntourists' satisfaction. The findings for these two variables were found to be in line with a study by Oh [26], who mentioned that the career function and social function do not significantly impact satisfaction. The career function has been understood as a status of profession among voluntourists, which was believed to have a positive relationship with voluntourists' satisfaction. It was believed that career may influence the voluntourists' satisfaction and this assumption is superseded in the context of this research. In other words, career status among tourists may only influence their choice of destination for vacations rather than for volunteer work. This is due to the usual high cost of travel and the amount of contribution towards volunteering work.
The social function was also found to be an insignificant factor towards voluntourists' satisfaction in this research context. The social function allows voluntourists to socialise among themselves and with local people. However, because most volunteers are tourists and only a few locals are involved in the activities, opportunities for them to mix are scarce. Furthermore, most voluntourists involved in this study came with colleagues, and socialising was the reason that they were involved in these activities. Moreover, voluntourists join voluntourism activities according to their own interest [24]. The focus is on the activities; thus, social function is only a bonus. Voluntourists can create a new network which does not affect satisfaction, provided that voluntourism activities are related to their interest.
Volunteer programs are important for island tourism sustainability; as such, programs can potentially generate a new market segment and effectively benefit destinations that require tourist voluntary work. Tourists are important to create awareness campaigns on the destinations through word of mouth, by sharing activities and expertise to reduce the environmental impact on the destination, and most importantly through knowledge exchange between tourists and local communities. These exchanges could have future benefits for the communities. Volunteering work can be seen as a medium of exchange in a social context, where tourists offer their time, efforts and skills to assist with an event or work as an exchange for experience which benefits them in return. Hence, voluntourists engage with other visitors especially if they believe that they could directly benefit despite extra costs. In doing so, they may be satisfied, which results in positive attitude, thus leading to continuous intention and the intention to recommend.

Conclusions
The literature review confirmed that voluntourists consist of a distinct group of people with varied backgrounds, skills and motivation, who seek for particulars of experiences [21]. It is a major task for the voluntourism organisations to fulfil these groups of voluntourists' expectation and satisfaction. Beyond satisfaction, there is a slim chance for voluntourists to recommend voluntourism to their colleagues and potentially will not continue to be voluntourists in the future. Owing to the importance of satisfaction on the voluntourists' future behaviour, the authors identified the factors influencing voluntourism satisfaction and the effect of satisfaction towards their future behaviour. Additionally, the literature on voluntourism is predominantly based on the Western setting [22], which is dissimilar to the eastern culture, and thus challenging to justify and apply in the eastern region [23]. According to Nesa, Ali and Rahman [22], there are a dearth of empirical studies conducted in the South East Asia region, focusing on voluntourists' continuation intention [24], particularly in the island destination setting.
In this research, a theoretically important addition was made on the extant volunteer tourism literature. Particularly, this research efficiently broadened volunteer tourists' approach decision formation by integrating an evaluation dimension (i.e., satisfaction). In addition, the factors directly and indirectly influencing this evaluation, and future approach decision formations were successfully incorporated into the proposed theoretical framework. To the best of our knowledge, the present research is the first empirical endeavour to explore and demonstrate the intricate associations among volunteer travellers' psychological functions, satisfaction, and behavioural intentions in the island volunteer tourism context. Given its constant growth, volunteer tourism is becoming a vital phenomenon in the tourism sector. Keeping pace with this phenomenon, our study offers a crucial guiding framework that helps academics and volunteer tourism practitioners to boost current and potential tourists' approaches and decision-making processes for volunteer tourism.
The authors acknowledge the limitations resulting from the purposive sampling that was employed. However, it was impossible to employ a probability sampling method due to the unavailability of a sampling frame [82]. Although the findings may not be generalisable to all voluntourists, they remain relevant to explain the satisfaction, the continuous intention, and the intention to recommend voluntourism to their connections. The findings should not be extended to other volunteering activities such as volunteering at sporting events or with non-profit organisations, because pure volunteerism and voluntourism have different characteristics and purposes for being a volunteer. Hence, the findings are limited to tourists who become volunteers at island destinations.
For theoretical contributions, the findings are underpinned by the rationale of the volunteer functions index theory; thus, the theory is applicable to the voluntourism context that covers their activities and community engagement at the destination. Moreover, the current study demonstrated that the career and social functions do not contribute to the voluntourists' satisfaction, as justified by the reasons above. However, in a context different from tourism, the social and career variables may contribute differently.
Implications for practitioners in the island tourism destination context include a better understanding of the antecedents and determinants of voluntourists' satisfaction which may contribute to a new market segment in island tourism as well as market diversification. Potential markets from European students or any youth tourists from four-season countries may be beneficial due to the different factors of geographic and climate offers in Malaysia. Furthermore, it is necessary for service providers to understand the voluntourists' decision making process that leads to satisfaction by re-engaging their experience with the activities they offer. It is a challenge for the service providers to meet the voluntourists' expectations. This could be achieved by exploring unique activities which widens the market attracted to participate in such programs. Service providers may also benefit from voluntourists who assist them with marketing, administration, experience, and ideas exchange between providers and voluntourists. Other potential markets to be explored include private companies or non-governmental organisations which may be involved in voluntourism activities combining such activities with vacations.
For future research, instead of using the career function, the authors believe that the income function may be significant to influence the voluntourists' satisfaction. This can be explained by the notion that high-income tourists may contribute more to volunteer work due to their passion to share and contribute back to what they assume is important such as environmental work, social work, welfare, and education, among others. Higher income of voluntourists translates to greater contributions towards volunteer work, thus leading to high satisfaction among voluntourists. Moreover, this may influence the voluntourists' continuous intention to pursue volunteering. Future research may expand the model to other contexts and destinations such as heritage or cultural sites to contribute to different outcomes and contexts of voluntourism in a tourism perspective. Future research may also focus on the willingness to pay among voluntourists who are involved in voluntourism activities resulting in experiences with different types of analyses and logical discussions.

Conflicts of Interest:
The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.