It can be seen that 1/3 of the world is deep sea. Although no one has an idea what those waters hold. Im sure that 1/3 of the world will be empty water tiles.
We need more stuff in deep oceans. We need to make people want to explore these wast uncharted territories. It shouldnt be used solely for feryying between continents.
My idea is small mythic islands that appear randomly. The idea can be expanded so much. The islands can be varying in sizes. There can be big ones that are permanent, with various unseen materials and creatures. There can be small islands that appear and disappear randomly. In the island there would be trees, rocks, clay, animals etc. that could go up to insane qualities depending on your luck. Of course the chance of finding this island will not be great either.
There could be human npc's in the game. Pirates, trade ships, vikings! that would sail along these deep waters. Which can be fought for their mysterious loots. Maybe gold and silver that the pirates ransacked. What good equipment can be found killing the pirate or viking leaders?. All the curios, silk, symbel that reside in the trade ship.
Limitless potential if you ask me.