Mar adentro (English title: The Sea Inside) is a 2004 film by the Chilean-Spanish director Alejandro Amenábar, written by Mateo Gil and Amenábar. Amenábar also produced and edited the film and composed the music, with the help of Galician musician Carlos Núñez.

The film, based on real-life events, stars Javier Bardem as Ramón Sampedro, a Galician fisherman left quadriplegic after a diving accident who fought a 30-year campaign in support of euthanasia and his right to end his own life. "Mar Adentro" has also been praised for its realistic and accurate display of the Galician people, language and landscape, something that stands the film out of what is normally the case in Spanish-speaking movies.

Mar adentro won the 2004 Oscar for Best Foreign Language Film, the 2004 Golden Globe for Best Foreign Language Film, and 14 Goya Awards including awards for Best Film, Best Director, Best Lead Actor, Best Lead Actress, Best Supporting Actor, Best Supporting Actress and Best Original Screenplay.