Beyond the Deep The Deadly Descent into the World's Most Treacherous Cave by William Stone and Barbara am Ende with Monte Paulsen Warner Books 2002, 6 by 9 inches, 351 pages, hardbound

This well-written book tells the story of the 1994 high-tech expedition that dove the sump in Sótano de San Agustín to discover another 3 kilometers of passage and restore Sistema Huautla to the deepest cave in Mexico, at 1475 meters. Illustrated with black-and-white and color photographs, drawings, and cave maps. Highly recommended. Publisher's list price was $26.95.