By far one of my favourite things in this game is the sunken ships. I love looking out for the birds, sailing over and diving down.
I believe there should be a contract where you have to retrieve cargo from a sunken ship. The ship shouldn't be marked by birds and should be deeper than usual so that other players shouldn't find it before you. (More common airpockets due to it being deeper). You find the merchant's cargo and return it for your reward. You find the ship by using coordinates on the map given to you by the quest. E.g. Search B9 for a sunken galleon, retrieve the exquisite spices that have been lost.
Thanks for reading!
