I'd like to see the ocean become another official biome, with progression elements built in for diving and a real boss. Sort of like how you need to get furs for the mountains. This way it makes it easier to risk battles on the ocean eventually if you can dive down and re-collect your wrecked ships and stuff. Real shipwrecks too, not just having your boat turn into a pile of mats but a sunken thing you have to harvest again and creatures and barnacles and stuff moving into it over time if you don't.

Typhoons, whirlpools, more sea hazards and monsters, ship to ship combat, I just really like the adventure feel of sailing and few other games do it at all much less well.