Offshore flooded caves, so-called ocean blue holes, are extensions of the sea, subject to the same heavy tides and host to many of the same species found in the surrounding waters. Inland blue holes, however, are unlike any other environment on Earth, thanks largely to their geology and water chemistry. In these flooded caves, such as Stargate on Andros Island, the reduced tidal flow results in a sharp stratification of water chemistry. A thin lens of fresh water—supplied by rainfall—lies atop a denser layer of salt water. The freshwater lens acts as a lid, isolating the salt water from atmospheric oxygen and inhibiting bacteria from causing organic matter to decay.
Until now, only a handful of scientists have ventured into blue holes, but in the summer and fall of 2009, a multidisciplinary cave-diving and scientific team spent two months studying them on Andros, Abaco, and five other Bahamian islands. Funded by the National Geographic Society in collaboration with the National Museum of the Bahamas, headed by Keith Tinker, the Bahamas Blue Hole Expedition was conceived by Kenny Broad, a veteran cave explorer and an anthropologist at the University of Miami. Under Broad's wisecracking, driven leadership, with Brian Kakuk as dive safety officer and preeminent cave explorer Wes Skiles shooting film and stills, team members made around 150 dives in dozens of blue holes. They gathered data that promise to deepen our understanding of everything from geology and water chemistry to biology, paleontology, archaeology, and even astrobiology—the study of life in the universe.
Read more here: Bahamas Caves - National Geographic Magazine.
Kudos to Dr Tinker, Michael Pateman, and all the others at the National Museum, my former colleagues. Hats off. Keep up the good work.