The animated film "The Red Tortoise" by Studio Ghibli is about a shipwrecked man who washed up on a deserted island. Like all castaways, sooner or later he would like to get away from the island and try a self-made raft. And this is where his "opponent" comes into play, after the film was named: a giant, red turtle that repeatedly manages to put an end to its attempts to escape the island.
But I don't want to reveal more here. If you don't know the film yet, you should get the DVD or Bluray: