The "hell island" referred to in the title refers to post-revolution Cuba. Some refugees are helped to the U.S. by an sea captain from Key West. He falls in love with a refugee's wife -- none of these refugees has an accent -- the husband is a psychotic crybaby, and he somehow talks the captain into talking him to the Bahamas so he can grub money from his sister. The husband tries to kill the captain and steal his ship.
If this sounds like a confused mess with no real plot, it's because this is exactly what it is. There's a scene that goes on for fifteen minutes where Mark Stevens (the captain) tries to get back on his ship after the psychotic guy knocks him into the ocean . . . which is filled with stock footage (badly patched in) of sharks.
Stevens directed this tiny-budgeted, black and white mess, which is supposedly based on a story by Robert Sheckley, a first-rate writer, who, I doubt, had much to do with this fiasco.
Watching this was about as exciting as watching Jello cook. No . . . it wasn't even that good. Skip it and pour that Jello powder in boiling water . . .