POŠK (POmorski Športski Klub: Marine Sports Club) is a Croatian water polo club from Split. The club was founded in 1937.
The club developed in a big name in the world of water polo, especially from the 1980s onwards, during which the national championship of Yugoslavia have been lost many times in points after tough "battles" against the remaining giants of the erstwhile Yugoslav and European water polo as Mladost, Jug, Partizan and Primorac Kotor.