Mysterious Island (1961)

Mysterious Island
Adventure, Science Fiction
During the US Civil War, Union POWs escape in a balloon and end up stranded on a South Pacific island, inhabited by giant plants and animals. They must use their ingenuity to survive the dangers, and to devise a way to return home. Sequel to '20,000 Leagues Under the Sea' .
Starring
Michael Craig, Joan Greenwood, Michael Callan, Gary Merrill, Herbert Lom, Beth Rogan, Percy Herbert, Dan Jackson, Harry Monty
Directed By
Cy Endfield