See this gallery of caverns, cave picturess and canyons. Also, don't miss this BetterPhoto article on digital exposure camera techniques.
Light at the End of the Tunnel
© MARLON IGNACIOAntelope Canyon
© Sue L. CullumberRainbow Canyon
© Kelvin S. MurphyA Photographer's Dream
© Priscilla J. Burgers... into the mystic
© Lyn E. AdamsGods' Light Beam
© Mike W. Detwiler