The coordinates listed in this thread and responses are NOT correct! I just completed the Pirate portion. First, for noobies, the Dock mentioned is the Dock you arrive when traveling to the Common Lands. The shipwreck is off the end of this dock a ways.
Note: If there are other players in the area, you may have to wait for the Pirates to re-spawn - there are only a few of them. Here are the coordinates where I killed my last Pirate: (-1141.06,-149,-854.41). If you "hover" here on the surface, you can see the shipwreck - you can also see the "ribs" of a ship's bow. The Pirates are generally located between the wreck and the ribs. Watch, and swim above the shipwreck if you need to. Use your mouse arrow to locate the Pirates and target them - they will appear to be small white dots. Then swim down toward the target, and attack with whatever weapon/spell as soon as it activates. Then quickly swim up to the surface. They will follow you and attack from underneath. You can easily kill them on the surface without fighting in the sea depths (as long as your Level is correct).
The game coordinates for the shipwreck itself: (-1101.48,-209.98,-850.84). Remember, only the Pirates will count! Happy Hunting!
Edited, Feb 5th 2009 11:10pm by NamVet