The islands of the Bahamas are all of a loosely cemented limestone, much of it dune ridges blown up at the time of the last Ice Age when the sea-level was lower. The rock is porous, and rain water seeps down through it to the fresh-water table below, dissolving as it goes. Small channels open up, and these become preferred solution paths which continue to widen. Soon the surface is pitted with sinkholes, from inches to feet across, called banana holes because they tend to fill with halfway decent soil and are ideal for planting a banana tree.
Where the freshwater lens was very deep during the Ice Ages, these sinkholes became very wide, and are called blue holes if they subsequently filled with sea water. Blue holes are favorites with divers. The largest dry sinkhole I am familiar with on Exuma is well-hidden on the jungly backside of the island. It is about fifty feet deep and as big as a basketball court (although approximately round). I have posted it before when I took a couple of grandchildren to explore. I was there again last week with two other grandkids.
We had to climb down a vertical cliff to get into the hole, which is filled with a wild variety of tropical plants, some rare, including giant air plants growing on trees. There are caves in the cliffs and "castles" -- huge chunks of fallen rock. It is impossible not to feel that we are in some Lost World, a visit to the Jurassic, perhaps. Was that a dinosaur we saw dart away from the murky pond?
There was no sign that anyone had visited the hole since the last time I was there. The approach road was in disrepair and almost impassable, the trail I cut out overgrown. My trail to another favorite place, the bat caves, was completely overgrown; I'll have to open it again before the next grandchildren visit.
Meanwhile, with all these wonders abounding, the tourists flock in to the new Four Seasons resort. They pay many hundreds of dollars a night to stay in a place that could as easily be in Florida or Cancun. The children spend all day frolicking in a generic pool, or playing computer games in the game room.