I think there should be a new proficiency seafaring.
It would unlock skills that allow for things like building harpoons, hunting whales from rowboats, building docks, and building the large boats we see in Providence.
The vast ocean should be as unforgiving as darkness. Risk of whales destroying your boat, fear debuffs the further you are from land, and increased risk of storms to drown you and destroy your expensive boat. Higher levels of skills would reduce fear and chance of your boat sinking in a storm.
You should be able to sell dried cod, and whale oil to NPCs. This is historically a large part of New England's economy.
Better yet once you are skilled enough you take the risk and sail your large boat to eastern end of map and sell goods to Britain.
You can sell the same goods to NPCs in London for more silver than in Providence. You can buy the same goods (and maybe some other cools ones like special clothes etc...)
Large boats could take several players just to steer. Maybe drowning deep in ocean constitutes permadeath or some nuking of character skills. It should be a very harsh trip, but the rewards should be worth it.