This is a weird one, on several levels: it's animated, and it has no dialogue, so there are no actors. And it's directed by a Dutch animator (Michaël Dudok de Wit) but released by Japan's famous Studio Ghibli.
A man is shipwrecked on a small island, where he finds food, water, cover, and a bamboo forest. He uses the latter to make a raft - but an unseen force destroys his raft each of three times he tries to leave the island. He's joined on the island by a woman (the "how" of that is what makes this a "Fantasy" movie), and they have a life together. And that's pretty much the whole movie in a nutshell.
I liked it and the animation is lovely, but I didn't find it particularly deep or absorbing - and, unlike the best of Ghibli, I don't expect to watch it again.