The paper deals with the positive law regulating the standards of prevention of pollution by sewage from yachts and pleasure craft and its specific application in the context of the ports of nautical tourism (marinas). The problem of pollution by sewage from yachts and other recreational craft is specific considering the large and increasing number of yachts sailing in Croatian waters, the particular technical characteristics of pleasure craft, the way they are constructed and certified, the manner in which they are used and operated, and the fact that the nautical ports in which the yachts and other pleasure craft are berthed are special purpose ports subject to a specific legal and management regime. Croatia, is a party to MARPOL, the main international convention covering prevention of pollution of the marine environment by ships. In particular, the standards of prevention of pollution by sewage are governed by MARPOL Annex IV. Whilst MARPOL regulates prevention of pollution standards for the larger vessels, most of the yachts and pleasure craft are outside its scope of application. However, these vessels are subject to the Directive 2013/53/EU on recreational craft and personal watercraft imposing mandatory installation of holding tanks to watercraft fitted with toilets. The relevant MARPOL and EU standards are implemented in the national law through the Croatian Maritime Code, the Maritime Domain and Seaports Act and the respective bye-laws, enforced through the flag and port state jurisdiction of the Republic of Croatia and the system of inspection control and sanctioning of maritime offences. The discharge of sewage into the sea is prohibited within the Croatian territory. The adequate port reception facilities must be fitted in all Croatian ports, including the ports of nautical tourism where it is a responsibility of the concessionary of the port. The authors critically examine whether and how the relevant pollution prevention standards are implemented in the context of yachting and marinas with a view of proposing certain improvements.