In the paper the authors present an accident investigation on a casualty happened in the Gulf of Naples during spring 2000. The environmental and navigation data during casualty are presented as well as capsizing and sinking are described in detail. Moreover the rescue operation following sinking and then the recovery operation of the boat are described. The authors highlight the reasons for sinking as emerged by Court investigation and give an example of a “report on the marine casualty” as requested by IMO MSC/Circ.827 (December 1997). Finally some suggestions are given in order to improve safety on fishing vessels.