The Museu de la Mar is a municipal maritime museum located in the Grao de Castellón (Grau de Castelló), the port district of the city of Castellón de la Plana. Its permanent collection documents the local seafaring culture and tradition through 274 pieces and more than 70 photographs related to the fishing activity historically carried out in the port.

The museum preserves material testimonies of the trades and customs of the Grao's fishing community: boats, fishing gear, utensils and graphic documentation illustrating the evolution of this activity over time. Its approach is ethnographic and educational.

The building is located on Carrer d'Eivissa, in the Grao district, and forms part of the network of municipal museums of Castellón (MUCC).

The institution offers educational visits aimed both at school groups and at visitors in general. Its municipal management integrates it into the city's stable cultural offer, complementing the historical heritage of the port surroundings.

The Grao de Castellón is one of the few fishing communities on the Mediterranean coast that retains an active seafaring identity, which gives the museum a living context within the Valencian Community.