The article reports on work reviewing research into cross-border tourism space as this relates to sea areas. In essence, the review made it clear that the matter in question only appears in the literature rather rarely, even as its underpinning concepts involving tourism space, borders, cross-border cooperation and international integration have been the subject of many studies. The Baltic Sea is no longer an area of separation, having become – more than ever – a meeting point of numerous political, economic and ecological interests. Within its basin (including adjacent areas of land and waters), cross-border tourism space is developing mainly as connections are formed between already-existing tourism space within given states – primarily coastal cities or regions. Connections via the sea confer physical shape upon maritime tourism space, by way of a banded pattern. In turn, cooperation between entities located on two (or more) sides of the maritime border plays a significant role in delimiting the boundaries of cross-border tourism space associated with sea areas, while also serving in the integration process relating to that space, which is actually more extensive than just the interconnected cross-border sea and the coastal spaces, given that cooperating entities may be located even beyond. The author argues that space in which the authorities, institutions and residents of two or more neighbouring countries make contact with each other by way of tourism as conceived broadly can be designated cross-border tourism space. If it is countries separated by a maritime border that are connected, then it is possible to speak of a cross-border tourism space linked to marine areas. The physical flow of tourists by ship that characterises the space in question (as tourist flows occur) provides further strengthening of the idea that such space is capable of being designated. This research forms part of work on aspects of border management and the development of cross-border management (by which a common, cross-border space, in this case for tourism, is developed). The author also posits the existence of cognitive tourism in relation to coastal areas: in cities (urban systems in coastal districts, ports, historic parts of cities, spas), and along the natural shoreline (visits made to coast, shore, dunes and cliffs). The work is then brought to a close with suggestions for further research on the topic, as based on an integrated approach embracing attractiveness, infrastructure and tourism flows, accessibility, the analysis of strategic and planning documents related to the development of tourism, tourism management, territorial marketing, regional identity, the creation of regional tourist products, cross-border cooperation relating to the development of tourism and the relevant impact of cooperation of this kind.