Since all of these are related then I will cram them all together.
Ocean itself - Deepen the ocean by like....A LOT. No more in the middle of an Ocean that is like 1000 blocks wide in some areas and seeing ground directly below you that you can stand on. Also extend the oeean further down in some areas, even up to like -100 blocks.
Tree: Palm Trees. Coconuts...On beach sand only. That is all.
New Sea Life:
1.Killer Whale " Hostile mob only when attacked.
2. Blue Whale - 20 block long Whale found only in very deep parts of the ocean.
3. Humpback Whale
4. Jelly Fish. They mostly float around and hurt you just like a sweetberry bush does. Maybe add in a poison status effect.
5. Sword Fish
6. Tube Worm
7. Angler Fish
8. Riftia pachyptila
9. Rock fish
10. Colossal Squid - only in abyssal zones.
Functioning ships A recipe that requires a large portion of materials to make the initial build. It first gives you the block item. Can only be deployed on an area with at least 30 blocks of water and it takes up 20. We could do a smaller one that is half that size. But once the ship is deployed then you have to craft the rest of the ship like the sails and stuff. Large ship could have like 6 canons, a crows nest and two lower decks. Smaller ship could just have one lower deck.
Also, this ship would come with the "Hammock" item which needs to be connected to two blocks, one on each side that is up space up from the floor at min. One person pilots the ship. Everyone else is free to ride on it. Your whole realm or server could be riding on it. When a person uses a canon it is a functioning canon that can destroy blocks, literally blow them away and kill other players and a large ship let's say can take 5 shots before all the blocks explode and falls into the ocean along with the players. When you use a canon it zooms out from the canon point of view. Canon Balls need to be crafted with Iron. Let's say 2 iron = canon ball. You can also blow apart other items in the game like stone, dirt, gravel, sand, trees, animals etc. Each canon explosion would do maybe like a 6x6 area if like, lets say you fire on a cliff.
This is important because if you had like a realm or server with like 10 people then 5 of you could Roleplay as Navy Marines and 5 others could RolePlay as Pirates.
The LOOM could be used to create flags. Pirate Flag could be a default flag you can just make. Symbols like crowns, tridents and other things could be an option for flag making.
One person could also be in the crows nest with a spyglass. We could Roleplay as PIRATES!