The Museu do Mar, Rei D. Carlos, to give it its full name; or the King Carlos Museum of the Sea is set near the centre of Cascais. It is a modern museum (opened in 1992) that embraces both traditional and modern multimedia style exhibitions.
Much of the museum's content relates to Cascais' relationship with the sea, although a good deal of this applies to the sea in general.
The museum is split into several themed rooms set over a couple of floors. Amongst the more local themes is the Cascais shipwrecks theme with exhibits recovered from some of the numerous wrecks along this stretch of coast near the very edge of continental Europe.
Another locally themed exhibition is the "People of the Sea" which documents the lives of those involved in the Cascais fishing industry through history.
Other, more general, topics are covered in the Oceanographic Science room and an exhibition entitled the "Sea and the Origin of Life". This exhibition was created with assistance from many prestigious museums and universities such as the Natural History Museum in London and the University of Lisbon.