L'enfant d'eau (1995)

A small plane crashes in the Caribbean, leaving only two survivors: a precocious teenage girl and a simple-minded grown-up. They end up on a desert island, with no inhabitants and no rescue in sight, and split. Then, a friendship bond develops between the two. The teenager, realizing she may not live long enough to see this experience, and the grown-up, never faced with this reality, soon fall in love.