We had to spend several days in Rock Sound, waiting for the wind to pipe down, so we did a little exploration of some of the many blue holes in the large and mostly shallow bay. Blue holes are collapsed caverns which have filled with water; they can be either inland, taking the form of nearly circular lakes, or underwater, where they stand out as vivid deep blue circles distinct from the pale color of the shallower water around them.

The Bahamian islands are riddled with blue holes of both types. One glance at the "ironshore" - limestone that's so full of holes it resembles (very hard and pointy!) Swiss cheese - and you'll see why: limestone readily erodes into caves. We've visited a lot of caves and blue holes all over the islands on previous trips - check out our logbook archives for pictures and stories.

Rock Sound has a large inland blue hole, the saltwater "Ocean Hole." Fish swim in it, and Britt and I swam in it too on our previous visit seven years ago.

This time we decided to check out the underwater holes, which are shown on our charts of the sound. (Rock Sound is the name of the settlement - the largest in Eleuthera - but it's also the name of the 4-mile by 1.5-mile bay.)

We started out by dinghying to one of the visible caves on the shoreline. It went back into the cliff for maybe 30-40 feet, but there was no sign of habitation either by humans or bats. Then we returned to the dinghy and slowly made our way south along the shore. As we approached the indent of a small bay with a sand beach and a house, we immediately noticed that the aqua water turned a much deeper blue right in front of the beach - a blue hole!

When we got closer, we could see that it wasn't so much a hole as a crack. Imagine opening a can of soup, running the opener not quite all the way around the rim of the lid. Then push the lid inward: it's still attached at one end, so it slopes down into the can, and at the deepest end there's a curving crack between the lid and the side of the can that leads down into the dark murky recesses of...soup.

In the case of this blue hole, it was fish soup. We dropped the dinghy anchor in the sloping sand of the "tin can lid," drifted over the deep crack, put on our masks, snorkels and fins, and jumped in. We dove down about 25 feet, past two groupers, to where the crack revealed itself to be a cave - continuing down and back under the surface of the shallows, and here my can metaphor breaks down, because that's outside the can. We couldn't tell how deep or how far the cave went. Another, smaller
cave under the "tin can lid" headed back toward shore, and looking at the chart I wonder whether it connects to the ocean hole.

After both of us had gone into the mouth of the cavern as far as we dared (not far), we got back in the dinghy and headed out to another suspiciously dark and shimmering spot of blue. This second blue hole was far out in the sound, another tin-can-lid crack with an overhung cave stretching back into darkness. Lots of fish swarmed here, including a small school of Atlantic spadefish (really cool-looking stripy fish shaped like the Ace of Spades) and a curious Almaco jack who followed us around as
we dove and swam.

On the way back to the boat we saw two more blue holes, and I wouldn't be surprised if there are more scattered across the bay. They are distinct when you see them - the dark blue of 30-50 feet of water really stands out from the 8-foot surroundings - but unless you're looking down on them, they're hard to spot at a distance. But they're definitely worth finding!
- posted by S/V Windom @ 4/27/2007 [link]