Yes, Mammoth Cave in Kentucky. Lovely long hike thru the cave..takes a couple of hours. Almost 20 years ago I went thru on a tour that took you down into a deeper section that was to the river that still runs through it. Glassbottom boats that you could watch the fish swimming under you. Really cool. But they stopped that particular tour because it was polluting the river too much. <!-- s --><img src="{SMILIES_PATH}/icon_sad.gif" alt="" title="Sad" /><!-- s -->
