The cave is located on the westside of the island short before Cove. Here was living the infamous captain Henry Morgan and his crew.
Unfortunately you can't visit the cave itself because the water level raised and the whole cave is under water, but the entry of the cave is worth seeing and anyway one get the the feeling how it was back in time.
There is a museum where one can get very good informations about the history of the island. During your whole stay you have a guide at your site who explains everything (English and Spanish).