Nautical tourism began to develop thanks to the natural conditions of development, the market, economic and institutional conditions, and the protection of natural resources. People sail for fun and tourism. Croatia as a tourist country builds its image on natural conditions, clean sea, protected nature, Mediterranean climate, cities and towns with a rich history, a large number of bays, layout of harbors are only one of the reasons why tourists come on vacation. The purpose of the work is to reach a conclusion about the impact of charter activities on tourism, analyzing the legal basis, the activity itself and sustainability. The goal of this research is to provide a theoretical contribution to the understanding of charter tourism and draw relevant conclusions that will support the sustainable development of charter tourism in the Republic of Croatia. The purpose of the research is to accurately evaluate the sustainability of charter tourism and to recognize regulatory challenges related to the installation of black and gray tanks on charter ships. The paper examines the importance of sustainable nautical tourism in Croatia and its impact on the environment. Croatia has favorable natural conditions for nautical tourism, and the diversity of the coast, the number of islands and favorable conditions for sailing make it an attractive destination. The text considers the development of transport infrastructure and the connection with tourism and explores different forms of nautical tourism, including chartering and cruising. The seasonal nature of charter tourism and the impact of the COVID- 19 pandemic on this sector are emphasized. The TOMAS survey on nautical tourists in Croatia continuously monitors the profiles and satisfaction of boaters, whereby Croatia stands out as a leading destination. The paper also explores the environmental challenges of nautical tourism, including the discharge of waste materials into the sea and onshore, and the prescribed environmental standards and CE marking for vessels. The work points to challenges and illogicalities in the Ordinance that regulates the nautical industry, especially in connection with the installation of containers for sanitary waste on older vessels. Furthermore, the example of Marina Punat stands out as a positive example of a responsible and environmentally conscious approach in nautical tourism. It is concluded that sustainable development is crucial for nautical tourism in Croatia, in order to ensure that tourism contributes to the preservation of the environment and the future sustainability of navigation.