The Blue Hole

The Blue Hole was a shipwreck site located in the Gibara region of the Caribbean. Home to several hostile species, including sharks and moray eels, it was explored by the pirate Edward Kenway during the early 18th century.

While searching the wreck, Edward managed to locate and loot several treasure chests that had sunk with the ship, gaining money and an upgrade plan for his own vessel, the Jackdaw.

Reference

 * Assassin's Creed IV: Black Flag