Yochib: The River Cave by C. William Steele Cave Books, St. Louis 1985, 7.5 by 10 inches, 164 pages, softbound

The exciting story of the exploration of the dangerous river cave Sumidero Yochib in Chiapas, to a sump at a depth of about 200 meters. Illustrated with black-and-white photographs, drawings, and cave maps.