A noncaver photographer friend of mine sent me this slide show of caves from around the world. Maybe you have seen it. I found the link but I could not get the sound to work. There might be an interface page. If so, click on view.
http://cid-32d3c06db7413d36.skydrive.live.com/self.aspx/Allegati/Presentazioni/FotoInsolite/zVoyageaucentredelaterre.pps .......... Sam
