It could be pretty fun actually. First you build your ship. So you get all sorts of wood, metal, etc. Then you sail, and discover new unmaped islands, battle with pirates, dig some treasure, go do some diving, find some new fishing spots and fish, discover eastern(asian-like) lands, new gear, host parties on your boat, team-work minigames, battle other players in boats, new dungeons, battle big sea monsters along the way, and so on. Would be amazing. Hmm they could even maybe tie it with Treasure Trails.