In spite the fact that composite materials have been in use in the maritime sector for over a half of century, classification societies regulations tend to limit the usage of composites at the larger scale. One of the reasons for such strict class rules is a lack of comprehensive analytical and numerical models representing the behaviour of composites in the sea environment. Understanding the process of degradation and damage of composite materials assisted by sea environment a crucial step in building such a model. This paper aims to give a critical review of the research advancements in assessments of the sea environment influence on the degradation of mechanical properties of composites with a special emphasis on developed models of processes containing water and moisture entering composite inner structure. The list of major references in the last five years is given and suggestions for future research are discussed.