1. Introduction
The cruise sector has been one of the most growing sectors in the tourism industry since it emerged in the late 1960s. According to Rodrigue and Notteboom [
1], this industry has become a crucial part of the tourism industry by using larger vessels and adding more passenger services on board. Globally, the ocean cruise industry had an average annual growth rate of 6.63% from 1990 to 2019 in terms of the number of cruise passengers [
2]. This sector has become one of the most dynamic and fastest-growing industries in international tourism [
3]. In recent decades, cruise ships have been deployed to many destinations around the world, from the Caribbean Sea, the Mediterranean Sea, and Alaska to Asia, because of the rapid growth of this industry. Focusing on the Mediterranean Sea, MedCruise [
4] reported that the number of cruise passenger movements in the Mediterranean increased from 17.56 million in 2018 to 19.53 million in 2019, which represents an annual growth of 11.2%. The cruise capacity deployed in the Mediterranean Sea, the second most popular destination region, was 17.3% in 2019, whereas in the most important destination region worldwide, the Caribbean Sea, it was 34.4% in 2019 [
5]. The cruise expansion in the Mediterranean market is due to several factors. First, the diversity of the Mediterranean region and the high density of ports have supported the cruise development, which enables innovative itineraries in a relatively small area. Second, several port infrastructures have been improved and modernized. Third, the climate in this region allows for a longer cruising season [
6].
Cruise tourism has a hugely positive contribution to the global economy. The global economic contribution generated by this industry amounted to
$154.1 billion in 2019 [
7]. This economic impact is especially relevant in those hub ports that have high homeport cruise traffic [
8]. Hub has different definitions in the fields of airports, seaports, and tourism. According to Lohmann et al. [
9], tourism hubs have been transformed into destinations because of the interaction of attractions, transport, and accommodation services they offer. In the case of cruise traffic, several areas can be distinguished: (1) Homeport, where the itinerary starts and ends. Depending on the type of itinerary, there is one homeport (the itinerary starts and ends at the same homeport) or two homeports (the homeport in which the itinerary starts is different in which it ends). (2) Ports of call, in which the ship usually remains docked between 8 and 9 h. Throughout this time span, the passengers visit the port’s tourist hinterland [
10]. The consideration of the homeport as the starting and ending ports of the itinerary is similar to the Lohmann et al. [
9] hub concept.
In setting up a cruise itinerary, one of the most important questions for cruise lines is ‘which port to visit?’ the final choice has a huge impact on the cruise line, the selected port, and other ports of the destination region. The answer could have economic, environmental, and social impacts in those ports [
11]. Cruise ships must have access to appropriate port infrastructures, superstructures, supplies, and services because the passenger’s satisfaction is the most significant reason to select the ports of the itinerary for a cruise line. The cruise ports are interested in being homeports for one or more cruise lines due to the positive impact generated on the port and the related city. Three sources motivate this positive impact: the cruise lines because they ensure traffic of this kind of vessel [
12], the cruise passengers and the ship’s crew increase the expenditure in the city, then becoming a source of income for the population [
13,
14].
Most studies about the cruise industry mainly focus on the following issues: the global cruise industry [
15,
16], sustainable cruise tourism [
17,
18,
19], problems with cruise ‘overtourism’ [
20], ecological problems related to cruise tourism [
21,
22], the geography of cruise traffic [
1,
23], port management [
10], passenger preferences on board [
24,
25], and cruise safety and security [
23,
26]. However, there is a lack of works that study the relationship between ports, as well as their competitive position within the set of ports in a destination region. In this sense, the works related to this field analyze the competition and cooperation between ports [
27,
28] or the way of modeling and evaluating the behavior of ports in a port network [
29].
In addition, the cruise industry sells itineraries, not destinations [
1] that are the principal element of cruise traffic [
30]. The itineraries have a notable influence on the occupancy rate [
31], and therefore those cruise companies that innovate their itineraries in different areas may attract more tourists. The higher number of tourists, the higher differentiation and profitability a cruise company has [
32].
COVID-19 Risk to Cruise
The health and well-being of passengers and crew are the fundamental priority for the cruise line [
33]. Before 2019, norovirus (Nov) and influenza outbreaks were the major health challenges for the cruise industry [
34]. However, since the end of 2019, the new coronavirus SARS-CoV-2 (COVID-19) has threatened the world. Specifically, the first cruise ship affected by this virus was the Diamond Princess at the beginning of February 2020 [
35]. A month later, at the end of March, at least 25 cruise ships had confirmed COVID-19 infections, and ten ships remained at sea, unable to find a port that would allow them to dock [
36]. Additionally, during the second half of March 2020, the cruise fleet around the world stopped its activity due to the outbreak of COVID-19, which was an unprecedented episode for the cruise shipping industry. Until the development of vaccines, COVID-19 caused an unprecedented health-related risk that evolved into a large-scale crisis for the cruise industry.
2. Aim and Structure of This Work
As mentioned in
Section 1, one of the most relevant issues that cruise lines have to deal with is passenger comfort and pleasure. Accordingly, cruise lines must offer good onboard facilities and itineraries that contain attractive ports for the passengers they carry on board. Therefore, not all ports generate the same interest in the cruise passengers; as a consequence, there are high-impact ports that cruise passengers want to visit (attractive ports). The ports that have less impact, but are connected with attractive ports, will gradually increase their importance. The present research focuses on the cruise port network in Southern Europe composed of ports located in the Mediterranean Sea and in the area of the Atlantic Ocean close to the Mediterranean. We have selected ports in Southern Europe to carry out the research because this area registers the highest concentration of cruise traffic in Europe. The goals of this research are (1) to explain the dynamics of the cruise port network for contemporary cruise ships in Southern Europe in terms of the centrality of the ports and the connections between ports, and (2) to obtain a series of graphs with the inter-port relationships of the sample of ports analyzed. To this end, the technique of social network analysis (SNA) is applied.
SNA provides a standardized statistical summary of the properties of a collection of objects (nodes) and the connections (edges) between them. It provides insight into patterns in spatial connections, in addition to the importance of nodes to local and regional connectivity [
37], not possible from traditional statistical methods without graphical representation. The application of graph theory, on which SNA is based, is considered of high potential to determine the connectivity among the ports analyzed. Therefore, we choose SNA as the analysis technique based on its understandability and generation of practical results. The relationships revealed through SNA can shed light on principal characteristics and influences in the contemporary cruise port network of Southern Europe, both quantitatively and graphically, which is the main novelty of this study.
The cruise market can be considered dynamic due to its rapid and constant transformation. It is for this reason that, to identify and understand behavior patterns in the cruise port network to be analyzed, it is necessary to consider a long enough time series. The novelty of this study is that the period of analysis is from 2015 to 2019, which allows us to perceive the changes in the network and understand them. Additionally, with the analysis of such large time series, it is expected to obtain results with a high degree of precision, which leads to a better understanding of the evolution of cruise itineraries. These results provide cruise lines and ports with important information to make strategies to attract more passengers in the development of new itineraries.
The article is structured as follows.
Section 3 is dedicated to the features of the database used as input data and the methodology applied to perform social network analysis to estimate the different metrics of the cruise port network.
Section 4 and
Section 5 include the results obtained and their discussion, respectively.
Section 6 presents the conclusions, limitations, and future perspectives of the research.
5. Discussion
Figure 3,
Figure 4,
Figure 5,
Figure 6 and
Figure 7 confirm the trends presented in
Section 4 and show the interrelations of the contemporary cruise port network. In the development of the research, we have faced the difficulty of the unavailability of the information of some ports that register high cruise traffic activity, such as Civitavecchia, Marseille, Naples, or Venice. Barcelona, Palma, Marseille, and Valencia are four of the most relevant European ports in the contemporary cruise port network. Barcelona and Palma have higher metrics than the following ports in terms of outgoing and incoming centrality degree, incoming and out-coming degree, and hub index. Despite this, both ports show an evolution, with very low variation of their metrics. Furthermore, although the time series of cruise calls of Marseille could not be analyzed, this French port represents a key performer in contemporary cruise shipping in Southern Europe. Specifically, the strong connection with Barcelona and Palma de Mallorca explains the relevant position obtained for Marseille, see
Figure 3,
Figure 4,
Figure 5,
Figure 6 and
Figure 7. Additionally, the intense connections between Barcelona and Palma de Mallorca and Marseille and Valencia lead to the high hub index obtained for the last two ports. Graphs reveal that these ports are key performers of the cruise traffic in the Western Mediterranean. The results lead to strong connections between Barcelona, Marseille, Valencia, and Palma de Mallorca. These connections are repeated year after year, see
Figure 3,
Figure 4,
Figure 5,
Figure 6 and
Figure 7. In addition, these four ports connect with ports situated in the Atlantic Ocean and in the eastern part of the Mediterranean. For instance, in 2018, Barcelona had connections with Santa Cruz de Tenerife in the Atlantic Ocean and Valletta in the central part of the Mediterranean, see
Figure 6.
The two most important ports in the Adriatic Sea are Dubrovnik and Venice. The flow of cruises in these two ports is high enough to put them among the ten most visited ports. On the one hand, the strongest connections are with ports situated on the shores of the Adriatic Sea. For instance, connections between Dubrovnik, Venice, and Bari are the most relevant, see
Figure 4. They are separated by proper sailing distances leading to a sailing time of approximately 7–8 h, which explains the intensity of the connections between them. On the other hand, betweenness metrics are low because this area acts as a destination region in itself. The sailing distance to reach the gateway of the Adriatic Sea that connects to the Western and Eastern parts of the Mediterranean makes it difficult for the Adriatic ports to connect with ports of the adjacent areas of the Mediterranean. Therefore, the betweenness centrality becomes lower. In this sense, only the port of Dubrovnik ranks among the top 15 ports in terms of betweenness centrality. It serves as an intermediate call in itineraries that sail between the north and south parts of the Adriatic Sea. Although, some connections with ports of the Eastern Mediterranean are identified, for instance, with the ports of Corfu, Katakolo, and Piraeus, see
Figure 5. The results obtained indicate that there are itineraries only composed of Adriatic ports and those that combine Adriatic ports and ports of the Eastern Mediterranean.
Santorini, Mykonos, and Piraeus are must-see ports in the Eastern Mediterranean. The flow of contemporary cruises and the centrality degree rose in these three Greek ports during the period analyzed, especially in Santorini in 2019. There has been an expansion in the Eastern Mediterranean market because of the higher number of connections there, especially between Santorini and Mykonos. In addition, the connections to and from Mykonos, Santorini, and Piraeus are, basically, with ports of the Eastern Mediterranean, see
Figure 6 (lower left corner). The need to reach a balance between sailing distance, length of the itinerary, and call at attractive ports in the contemporary segment may explain the greater number of connections that Eastern Mediterranean ports register among them, but not with ports of other areas. Moreover, the lack of connections between ports of the Eastern and Western Mediterranean is explained by the excessive itinerary’s length for the contemporary segment.
In addition, Civitavecchia, Naples, Ajaccio, and Valletta have the role of transit ports because they connect the contemporary cruise traffic between the Western and Eastern Mediterranean Sea. These ports connect with the most relevant ports in both regions, for instance, in the west with Barcelona, Palma de Mallorca, and Gibraltar, and in the east with Santorini, Corfu, and Katakolo. The role of transit ports is also observed in ports of Northern Europe. Southampton, Amsterdam, and Hamburg act as transit ports in that region, connecting with ports of the Atlantic Ocean, see
Figure 3 (lower left corner) and
Figure 4 (central upper side). The results also highlight the role of the ports of the Atlantic façade in interconnecting ports of the Caribbean Sea, Northern Europe, and Mediterranean Sea. Among them, the ports of Funchal, Gibraltar, and Lisbon are highlighted, see
Figure 5 and
Figure 6.
The most relevant ports, according to the average incoming degree for the period from 2015 to 2019, are Barcelona (23), Palma de Mallorca (20), Málaga (20), Lisbon (19), and Santorini (15). In the case of outgoing degree, the ports with the highest metric during the period from 2015 to 2019 are Barcelona (27), Málaga (21), Palma de Mallorca (20), Lisbon (19), and Dubrovnik (16). The above results reflect the huge impact of cruise shipping from/to a specific port; it has two effects: the number of different ports that each port connects to and the number of times a specific connection is repeated. For instance, according to the results obtained, 27 ports (318 interrelations) are connected in the flow initiated from Barcelona, and 23 ports (333 interrelations) are connected in the flow received by Barcelona.
The betweenness centrality is a metric that could be unnoticed, but it can identify some behavior patterns in the network that are relevant. Barcelona (0.143), Lisbon (0.126), Amsterdam (0.106), Malaga (0.105), and Santorini (0.086) are the most important ports in terms of betweenness centrality. Moreover, Civitavecchia is the port with the highest betweenness centrality degree, whose results are obtained from the analysis of ports with available data; specifically, it has the twelfth highest betweenness centrality degree (0.055). Therefore, the contemporary cruise segment operates around Barcelona, Civitavecchia, and Malaga in the Western Mediterranean Sea. Amsterdam has a similar role in Northern Europe, as with Lisbon in the area of the Atlantic Ocean close to the Mediterranean, and Santorini in the Eastern Mediterranean.
From the point of view of hub and authority roles, Palma de Mallorca is considered a hub port because it has the highest hub index. Specifically, the results of Palma de Mallorca can be interpreted as it has cruise service to high-impact ports based on the yk values obtained. In contrast, the explanation of the classification of Barcelona as an authority port is explained by two indicators. First, it has the highest number of cruise calls of the ports analyzed. Second, the values of xk obtained mean that Barcelona receives cruise services from impact ports. In addition, the evolution of the port of Marseille regarding its role as a hub and authority should be noted. During the period 2015–2017, its activity was mainly associated with services to high-impact ports. This trend changed in 2018 and 2019 to higher values of xk than yk; therefore, its role is more associated with authority than with hub.
The results obtained in this research could be of interest to itinerary planners to identify the roles of the different ports in Southern Europe. These results are interesting for developing new itineraries that face the new challenges that the COVID-19 pandemic has introduced to the cruise industry, especially in terms of the flow generated and received in each port, the inter-port relationships of the contemporary cruise port network in Southern Europe, and the intensity of inter-port relationships. Specifically, the results obtained in this work could be the basis for developing research on the carrying capacity of ports and designing itineraries that seek to avoid overcrowded destinations, which is one of the main challenges faced by post-pandemic cruising.
Furthermore, through the inter-port relationships and connections obtained in this work, the design of new itineraries focusing on repeat cruise passengers could be addressed. Regaining the confidence of cruise passengers after the COVID-19 pandemic is another issue to address [
71]; the values of centrality degree obtained could be considered to develop attractive new products based on new ports. In addition, the inter-port relationships mapped (
Figure 3,
Figure 4,
Figure 5,
Figure 6 and
Figure 7) could be of interest to the stakeholders of the supply chain of the cruise industry to assess their impact and seek new areas of influence. Finally, a graphical representation of inter-port relationships could be used in studies of environmental assessment of cruise traffic.