Extreme Cave Diving by NOVA, aired 2010
2:30 p.m. 2/22/2013
Extreme Cave Diving
In this video Kenny Broad (anthropologist, National Geographic explorer), Brain Kakuk (one of the worlds most experienced cave divers), and Wess Gials (professional photographer) take us into the depths of Blue Holes. On two islands in the Bahamas named Andros and Abaco, they explore seven Blue Holes. Within these caves we see the dangers, structure, and artifacts these professional divers live for. Blue Holes get their name from the dark blue of their depths, that can reach thousands of feet. The Bahamas are the most common place on earth to find Blue Holes. This is because the islands are made of limestone and coral. Three-thousand years ago during the last Ice Age the level of the ocean was 400 feet lower, leaving much more land exposed, including the Bahamas. When it rained on the islands, the water cut deep caves straight down in the limestone. After the Ice Age, when the level of the ocean began to rise, the caves began to fill up with saltwater from the bottom and fresh water from the top. Where the saltwater and fresh water meet is called the halocline. At the halocline a chemical reaction happens that is corrosive enough to eat away the walls of the cave. This could happen multiple times within a Blue Hole causing tunnels to form horizontally that many divers get trapped or lost in. A hundred feet or so below the halocline the water becomes void of oxygen. Blue Holes are covered in a rich silt that can be very hazardess to divers that disturb it. On average 20 divers die each year from cave diving. Extreme cave diving is very different then other types of diving. When you make a find, get in trouble, or think your done you can't swim straight to the surface. You have to go back out the way that you came. That makes it a much more particular and serious sport. The rich silt that covers the floors, walls, and ceilings of Blue Holes...