Assassin's Creed Black Flag Havana key is gone, my plot is cleared, the map is fully opened, and everything on the road is obtained, except a templar assassination to grab the key.
You should have got the key to Havana. The last key is on the island in the lower right corner of the map. Some of them are named Cayman Port, and the island for subsequent missions is called Pinos Island after coordinates 397 and 324, and 335 and 469 are directly above Cayman Island. Take a quick trip to these two places. It may not be displayed on the map.