I would like to be a sailor and/or pirate and take contracts to deliver goods and board transport ships. That would require real time sailing, of course.
An easier to implement profession that I would enjoy is cartographer/treasure hunter. Various npcs from traders to military would hire me to find uncharted places, hidden caves, natural resources on the map, giving me vague directions and paying big for hard finds. The underwater world would be much more interesting if we'd be sent to find sunken treasures.




Well, it's illegal over here, so I don't know what you're talking of. 



