Ambergris Key

Ambergris Key, located on an island off the coast of Belize, was one of several smuggler dens in the West Indies. It was found and robbed of its supplies by the pirate Edward Kenway during the early 18th century.

Ambergris Key consisted of a complex of abandoned Mayan ruins carved into a large cavern, which opened up to a small cliff overlooking the sea. They could be accessed through a series of underwater tunnels, populated by jellyfish and sea urchins.

The ruins were at one point pillaged by a group of smugglers, led by a Templar aristocrat. Said individual was subsequently assassinated by Edward as part of an assassination contract.

Reference

 * Assassin's Creed IV: Black Flag