Classicly

Imagine an episode of Lost mixed with the movie Jurassic Park and you might have Edgar Rice Burroughs' classic book The Land That Time Forgot. Set during WWI, it features a German U-boat with British captives that goes off course and gets sucked into the current of a "crater lake."

Somehow through a freak geological and evolutionary glitch, the island is covered in dinosaurs and proto-humans. Follow the pair of cast-aways Bowen Tyler and Lys La Rue as they set up "Camp Dinosaur," fight off bands of humanoids, discover oil for the Uboat (seriously!), and play house together in a sort of neo Adam and Eve in paradise scene.