Cut off from the rest of the world, animals living in caves have become specialists adapted to living with sparse food, complete darkness, and acidic conditions. Such limited resources have forced cave dwellers into important and distinctive niches in their ecosystems. Water also plays a large role in the environment by offering a home to many species as well as forming caverns and such prominent cave features as stalactites and stalagmites. Traveling with experienced divers, the presentation tracks dangerous expeditions through largely unexplored subterranean regions of Mexico's Yucatán Peninsula and New Mexico to reveal unique underwater passages and crystal-lined caverns. Running time: 52 minutes. Available to U.S. Customers Only.