Richard Widmark is on quite good form here, as the veteran naval officer hired by a group of scientists to take a ramshackle old submarine from Japan to investigate some mysterious goings-on on an island under Chinese control, and where they think atomic experiments may be taking place. Setting sail with "Prof. Montel" (Victor Francen) and his assistant "Denise" (Bella Darvi) it soon becomes clear that their scarcely functioning vessel is not going to be the captain's only concern as they have to dodge enemy patrols and reach their target. I like submarine films, and this one isn't bad. Samuel Fuller takes a while to get us underway, but once he does the trip is quite exciting despite the odd romantic interlude. The ending is a bit daft, but the whole film still holds up quite well as a decent adventure with quite a fun underwater duel, an unique rendition of "Don't Fence Me In" and a suitably rousing score, too.