Go to freetown and try to sink the 81k ton huge european liner like what i did
Sunk 2 so far, but one of them was just off the coast of england and using my deck gun as well lol!!! Idk why the ship didnt try to outrun me instead when i hit it with the deck gun :P
Alternatively go to greenland or norway and try to sink convoys while it almost daylight all the time. Quite a challenge!