I recognize that this is actually partially answered here but I thought this was worth asking on its own for an answer that addresses it directly.
Maui is stuck on an island for a thousand years. We also know that he is an expert wayfinder and seaman. I'm not saying that necessarily makes him an expert boat builder, but after a thousand years you would think he would have been able to build something reasonably seagoing. Perhaps during that time he tried and was always pushed back by the sea somehow as punishment for actions, and so he knew he needed to wait until the gods showed their forgiveness by giving him a boat as a sign that he was finally allowed to leave, but that wasn't shown in the movie at all. So are there any behind the scenes info or cut scenes or anything like that which indicates why he didn't just leave the island?