The Prisoner of Shark Island : Does anyone know where this was filmed?

My dad swears that this was filmed at Rikers Island in New York City, but I'm not entirely sure. Can anyone confirm this?

Jeanie

Dry Tortugas, south of Key West Florida. Fort Jefferson is still there and is a national park.

There is no way on the face of this planet that this movie was filmed at the Real Fort Jefferson. It is 60 miles South West of Key West, the only way to get there is either boat or seaplane. No fresh water but what is caught in a cistern, no electricity and no accomidations for any one, let alone a cast of this size.
This picture must have been shot on a sound stage, but they did a resonable job of recreating the Fort, thought there are almost NO building inside the walls, as there are dipicted in the film.

The entire prison and moat were built expressly for this film on a Hollywood sound stage,filming from Nov.12,1935 to early Jan.1936.Released Fen. 12,1936.