The lighthouse on Great Isaac Cay, a small island in the Bahamas around 20 miles north-east of the Bimini Islands, was built in 1859 to guide trade-ships carrying exports of sun-dried sea salt from Inagua, rum from Nassau, and aragonite lime-stone to markets in the US. The lighthouse, though scoured by the sea and surrounded by the tumbledown buildings of the keeper’s house, is actually still in operation as an unmanned light. A tiny island not even visible on Google maps. Local lore tells of ghostly noises swelling about the lighthouse during a full moon- apparently the spectres of a …