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 local maritime culture and tradition through 274 pieces and over 70 photographs related to fishing activity historically developed in the port.

The museum gathers material testimonies of the trades and customs of the fishing community of the Grao, encompassing vessels, fishing gear, utensils and graphic documentation illustrating the evolution of this activity over time. Its approach is eminently ethnographic and didactic.

The building is located on Carrer d'Eivissa, in the Grao district, and is part of the network of municipal museums in Castellón (MUCC). The contact telephone number of the associated tourist centre is 964 73 74 33, and the reference postal address is C/ Joan d'Austria, 18B, 12100 Grau de Castelló.

The institution has an outreach vocation and offers educational visits aimed at both school groups and general visitors. Its municipal management integrates it into the city's stable cultural offering as a complement to the historical heritage of the surrounding port area.

The Grao de Castellón is one of the few fishing centres on the Mediterranean coast that preserves an active maritime identity, which gives the museum a living and unique context within the Valencian Community.