Tourism is a multifaceted concept (Parfinenko et al., 2019; Prokopenko et al., 2019). Even if we consider the sector of international marine tourism, a wide range of issues and approaches that determine its prospects and trends can be observed in the scientific literature. Marine tourism includes numerous services, such as marine tourism companies, cruise companies, charters, ports, the underwater tourism industry, shore service, etc. Furthermore, the role of governance at all levels, including schemes, laws, guidelines and concepts, public leaders and the scientific community, cannot be underestimated in the development of international marine tourism. Tourists themselves, the population of tourist regions and their level of social and economic development also play an essential role in tourism development. In addition, tourism is closely related to the natural environment of seas and oceans, as well as coastal areas, because the purpose of most tourist trips for recreation is close contact with nature.

Sustainable development is a fundamental principle of developing countries as a whole, as well as industries and territories (Shvets et al., 2023; Prokopenko et al., 2021; Prokopenko & Miśkiewicz, 2020). Sustainable development as a socio-ecological-economic development priority is associated with the Scheme for international cooperation, the 2030 Agenda for Sustainable Development and the Sustainable Development Goals (SDGs) (United Nations, 2015). The concept of sustainable tourism is fully included in the Global Code of Ethics in Tourism, the implementation of which among its member countries is organized by the World Tourism Organization (UNETO).

Bibliographic studies of scientific publications devoted to marine tourism have recently been carried out by numerous authors. In order to determine the state and trends of the coastal and marine tourism (CMT) industry, a study by Duan et al. (2022) was devoted. The researchers conducted a qualitative bibliographic analysis of publications for the years 1990-2020, taking into account such variables as: Productive Countries, Organizations, Authors, Subject Categories and Main Source Journals and Keywords. Connections between them were also established. As a result, the main research topics were identified, namely: (1) the sustainable development of CMT, (2) the impact of CMT on destinations, (3) CMT management and conservation, and (4) the impact of climate change on CMT.

Selvaduray et al. (2022), based on bibliometric analysis, identified the main clusters of problems that the maritime tourism industry suffers from. They were (a) governmental and political support, (b) environmental issues, (c) cooperation among stakeholders, (d) maritime tourism law and policies, (e) technological matters, and (f) maritime tourism knowledge. This study proposes a smart maritime tourism market, the study defines Smart Maritime Tourism (SMT) as a new type of maritime tourism that employs Virtual Reality (VR) to encompass and change the foreland, seaport, and hinterland segments of the industry (Selvaduray et al., 2022).

The study focused on the conceptual apparatus was carried out by Martinez Vazquez et al. (2021). The authors followed the evolution in the Number of Publications per year in relation to the terms “nautical tourism”, “maritime tourism” and “marine tourism”. They identified the most cited articles, productive authors, affiliations, countries, regions, and relationships. In our opinion, the main result of this study is the categorization of the concepts of "nautical tourism", "maritime tourism" and "marine tourism" and the identification of the need to define a new concept of "blue tourism". A new concept was proposed that integrates the subsector of the blue economy and the blue growth strategy, under the name of “blue tourism”, with the sea as the protagonist and all those tourist activities of leisure and recreation developed in this environment.

There are studies of trends in eco-tourism and sustainable tourism (Shasha et al., 2020; Mauleon-Mendez et al., 2018; Garrigos-Simon et al., 2018, etc.), but they do not touch on the topic of coastal and marine tourism. The development of marine tourism in combination with the socio-ecological and economic development of territories and countries as a whole in order to maximize the socio-ecological and economic benefits of tourism and minimize its negative impact on nature and society is a priority of many scientific studies.

Our research aims to determine the trends of international marine tourism in the context of sustainable development priorities with the help of bibliographic and contextual analysis of scientific literature. Also, the goal is to present possible prospects for developing international marine tourism based on the conclusions and recommendations of selected scientific publications.

The research methodology consists of bibliographic and content analysis of relevant scientific publications investigating international marine tourism aimed at sustainable development. We used the Dimensions research information database search engine for bibliographic search and analysis. The database searches among Publications, Grants, Patents, Clinical Trials, Policy Documents, and Records with Altmetric attention. A total of 153 million research records were searched [Bode, 2019].

A wide variety of terms refer to marine tourism and sports, recreational activities at sea and in other aquatic environments, international sea voyages, walks and trips along coastal waters and other activities that can be attributed to marine and coastal tourism. Definitions of the most used terms such as “nautical”, “maritime” or “marine” tourism often overlap each other's spheres of definition. A rather detailed study of the categorizations of these and other terms was conducted by the authors Martinez Vazquez et al. (2021). Since for the purposes of this study, it is not important enough to clearly establish the difference between the definitions, we will use the term "marine tourism" for the search and analysis, and have in mind a very broad concept, based on the category "blue tourism" (Martinez Vazquez et al., 2021) with the sea as the protagonist and all those tourist activities of leisure and recreation developed in this environment.

Search using Dimensions on the intersection of two key phrases in the title and/or abstract of the article "marine tourism" and "sustainable development" results in 949 publications. The search was carried out on the request "marine tourism and sustainable" since it includes unfinished phrases such as "sustainable development", "sustainable economy", "sustainable tourism", etc. Publications from 1973 to 2022 are included in the search. The found publications consist of 750 Articles, 133 Chapters, 31 Preprint, 15 Edited Books, 12 Proceedings and 1 Monograph [Search, 2022]. Additionally, Datasets from 1,424 sources, Patent 1 and Policy Documents 295,882 are available for analysis upon request.

Each publication belongs to a particular group of research categories. According to Fields of Research (ANZSRC 2020), dimensions implement automatic machine-based division into research categories. The Fields of Research (FoR) classification is a component of the 2020 Australian and New Zealand Standard Research Classification (ANZSRC) system. Each publication can be assigned to several research categories. Table 1 presents the results of the division of publications for a given search into groups of research categories according to Fields of Research (ANZSRC 2020). Most of the research belongs to the research category 41 Environmental Sciences (438 publications). The following categories have the most excellent results: 35 Commerce, Management, Tourism and Services, 37 Earth Sciences, 48 Law and Legal Studies, 31 Biological Sciences, 40 Engineering and 44 Human Society.

Table 1 The division of publications for a given search into groups of research categories according to Fields of Research (ANZSRC 2020).

Source: Authors.

Publications on topics at the intersection of marine tourism and sustainable development began to be published in 1987 (one publication). After that, for a long time, there were few publications on the intersection of the selected topics (one in 1989, two in 1993, one in 1995, two in 1996, two in 1997, and one in 1998) until 1999, when the trend of increasing interest in the given topic began. Since then, the most significant number of such studies was conducted in 2020 – 180 publications. Figure 1 shows the number of publications published each year. Here Publications is the number of publications related to the search. The analytical view shows the total number of related publications. The values per year are the years in which the publications were published.

Taking into account the wide variety of components of international marine tourism and the indisputable importance of increasing the socio-ecological and economic results of tourism, as well as the prevailing trend in minimizing the negative environmental impact of tourism on the natural environment, broad prospects for the development of tourism are opening up.

The content analysis of the selected publications makes it possible to talk about the need for management reforms at all levels through the concept of sustainable development and the Global Code of Ethics in Tourism. This goal requires the adoption by even more world countries of the philosophy of the Global Code of Ethics in Tourism and approximation to its standards. Moreover, it is also necessary to implement the mentioned concept in its political and economic strategies in the middle of the country at all levels of tourism development.

According to the results of the bibliographic analysis, it was evident that the development of scientific research aimed at implementing the concept of sustainable marine tourism and the Global Code of Ethics in Tourism needs attention.

The next problem is the clustering and externalization of marine tourism according to the orientation toward a particular community. Since the negative socio-ecological-economic consequences of tourism are borne by the territory and society of a specific local community, large-scale tourism, which is international marine tourism, is accumulated internationally.

Furthermore, finally, the blue economy and the protection of natural resources of coastal areas as a basis for implementing marine tourism activities need further development.

The results of this study can be helpful both to the scientific community and the general public, as well as to specialists in the field of bibliography.

Funding: The research presented in the manuscript did not receive external funding.

Author Contributions: Data Collection, Data curation, Research, Conceptualization, Methodology, Writing, Review, and Editing; all authors contributed equally.