-For added difficulty, you should start off a game with nothing! I mean you could swim and get the items to craft a hook
-Maybe tool durability
-More kinds of crops! (carrot, corn, or whatever)
-When you drop an item, it doesnt look like a barrel but maybe something
-Small islands maybe?
-birds? maybe for decoration or maybe use it for something
-shark must have lot of damage. i mean irl a shark wont kill ya in maybe more than 10 bites lol