The carribean treasure map is obtained from the New Sheepskin Scroll.
The treasure is located at Treasure Golf. You need to have a boat to get to this location. If you do not have a boat yet, you can purchase it from the Builder.
You need to board your ship in Magical Ocean. If you board at Shaitan City, the Wirlpool east of the little island in front of the harbor will take you to Treasure Gulf. (Picture 1) Head north for the docking place.(Picture 2) Double-click the treasure map and the locations of the treasure will appear in the system messages.(picture 3) Go to this location and double-click the map again. You will dig up the treasure. If it doesn't succeed the first time (system message will say "failed to use item") just keep on using the item until you will dig up the treasure. The system message will say what your treasure is (picture 4).
To leave the gulf and return to Shaitan city you can use the whirlpool at (724,1032)
Beware: sometimes all you get is a boobytrap which will cause considerable damage.