How do you find the ocean graveyard on endless ocean?

Well, you go to an open area in the water. You go up to the surface of the water and press A. You should be able to see the area above to water. Sometimes, you can see a faint white ship, or a pirate ship, quite close to you. Swim towards it and swim into one of the cracks in the side of the ship. Hopefully, a current will pull the ship away into some distant waters far away. It is then that you should arrive in an area that they call the Ocean's Graveyard. Make sure you search the area fully because there are some real treats hidden there. (By the Way, the faint white boat is just the same thing, but from a distance it looks like a white boat!) Hope my answer has helped you!