Marina Business, or Marina in&with Business is a new term in the terminology of nautical tourism, introduced in Croatia in the conditions of COVID-19. In other words, the COVID-19 pandemic has exposed the old, disorganized relationships of entities operating in and with marinas. The damaged relations during the pandemic showed all the illogic in their existing relations as well as the damage to the better results of Croatian charters and ports of nautical tourism, especially marinas. The fact that the state distanced itself from the economy and the development of entrepreneurship was reflected in the development of nautical tourism in Croatia, which developed independently in all its sub-forms after the Homeland War. Favourable post-war opportunities on the market of nautical tourism offer, i.e. lagging in the development of nautical tourism capacities and high dynamics of tourism demand, favoured nautical tourism enterprises that achieved positive business results until the outbreak of the COVID-19 pandemic. If the problem of cruising is excluded, both large world cruises and small domestic cruises, nautical tourism ports, especially marinas and charters, developed dynamically, but with the intention of doing profitable business, the problems gradually deepened. At the same time, the relationship problem could not be solved due to the good mutual business results. The emergence of the pandemic in 2020 showed the other side of the cooperative relationship between charterers and marinas, which for both subjects led to the distancing of the state in aid programs that should have been specific and not general for subjects of all types of businesses. In addition to the problems of charters and marinas, it is also necessary to consider the activity of skippers, who are of great importance for Croatian charter, which is considered the largest in the world. The services of skippers are used by about 40% of sailors, and they are an important segment for the success of the Croatian charter business. It should be noted here that in the further paragraphs of this paper the terms nautical tourism ports and marinas will be used, and this is because charter is mainly located in marinas and only to a lesser extent in other forms of nautical tourism ports, so it is also mentioned in nautical tourism ports. Thus, the relationship “marina-charter-skippers” represents a working symbiosis that links it to the intention of all successful businesses. The goal of the research is to valorise the factors of the quality of business cooperation and good business relationships that ensure profitable business for everyone. The research hypothesis states that the necessary good business cooperation can be achieved through a higher level of cooperation than before.