Originally published February 5, 2010 at 10:21 a.m., updated June 17, 2013 at 3:36 p.m.
"Extreme Cave Diving" follows a fearless team of scientists as they venture into blue holes—underwater caves that formed during the last ice age, when sea level was nearly 400 feet below what it is today. These caves, little-known treasures of the Bahamas, are one of Earth's least explored and perhaps most dangerous frontiers.
The interdisciplinary team of biologists, climatologists, and anthropologists, led by renowned cave explorer Kenny Broad, discover intriguing evidence of the earliest human inhabitants of the islands, find animals seen nowhere else on Earth, and recover a remarkable record of the planet's climate.
The stakes are high as the scientists swim hundreds of feet through narrow, dark passages that have trapped and killed divers in the past, but the scientific payoff is considerable.
This program originally aired in 2010.
Creatures of the Underwater Caves:
On the islands of the Bahamas, in a vast network of underground, water-filled caves, biologists have discovered remarkable fossil evidence of animals that once inhabited the region, as well as a host of small and intriguing creatures never before seen.
In this slide show, meet some of these animals, and learn why the caves, known as "blue holes," are likely to yield other unique finds in years to come.