Fort Lully, known previously as Navassa, was a British fort located on a small island off the coast of Jamaica, in the Caribbean. The island was located in a stretch of sea between the islands of Jamaica and Haiti; as such, vessels were forced to either sail within range of the fort's cannons, or be made to sail the long way around either island.
The fort was eventually besieged and overrun by Edward Kenway and the crew of the Jackdaw. After it had been captured, a harbormaster's station was built by the docks, where Kenway also accepted naval contracts on behalf of the trader Milo van der Graaff.
As of the 1730s, the island fort had yet to be re-garrisoned, and remained a ruin.
- The name of the island is derived from the Spanish word nava, meaning "plain, field, vale, dell" - although the island where the fort is located was rather rocky and varied in elevation.