Already impressed to come back after a few months and finding a load of new commendations to earn but I have a few more suggestions.
Some other liquid to drink besides grog (maybe giving benefits? Like a potion) and add a food and hydration meter. Add a risk of coming down with scurvy and eating fruit to keep it away (further expanding on the food meter). Add a gangplank to make transporting at an Outpost smoother. Add a grappling hook. Allow 3 ppl on a sloop, 4 on a brig, 6 on a galleon and the man o war can have 8+ put telescopes on random islands and add star searching commendations (noticed a telescope at devil's ridge, prime location) add some sort of firebomb (effective enough to put a hole in ships) and maybe some potions: maybe one to instantly heal scurvy, to give slight benefits like extended underwater breathing or damage resistance vs skeletons but not PvP. Some other things to add since we're already killing megalodons and Krakens: Whale Hunting. Orcas, sperm whales, blue whales and of course the white whale and one more thing. Dolphins, not hunting them but how cool would it be to sail with Dolphins?! Lots more ideas where that came from.