Prehistoric Isle in 1930

Ships have been mysteriously disappearing in the vicinity of the Bahamas for years. Now, in 1930, the United States government sends an expedition to the area in a flying boat to determine the cause. As they survey the ocean, the expedition comes across an uncharted landmass which they dub "Greenhell Isle" and launches two reconnaissance biplanes to take a closer look. As they investigate the island, the biplanes come under attack by dinosaurs and other life forms that were thought to have become extinct millions of years ago.