Why not add ship wakes to the game? For those of you may not know a ship wake is the trail created from contact with the water starting from the front of the ship and usually leaving a white trail in the back. It would would be a minor addition I think that would look great aesthetically.
It could even have a gameplay element to it. Like concealing a player almost completely if they swim in it or even providing another ship a little extra speed if they sail directly behind you; or perhaps slow them down, whichever fits the balance more. The trail wouldn't look exactly like modern ships but I think any wake would be cool.
Let me know your thoughts.

