If you have never been to this cave you have missed a treat.  Bob and I have visited a number of other caves over the years but nothing really compares to the size and variety of Carlsbad. Because it is a living cave (still forming) they are very careful about anyone touching anything since our body oils will kill whatever we touch. Even our hair and skin cells are detrimental so they ask that you not do any grooming while in the cavern! It is hard to imagine the size of this place. The Big Room is equal to 15 football fields! Because they can’t really light it all you can’t begin to get a sense of the size.  And that is just what they let you visit. There are miles of caverns not open to the public. We had neither one ever seen the Bat Flight so we went to the caverns in the afternoon (after they closed the Natural Entrance which is a 1.25 mile walk in), went down in the elevator and did the 1.25 mile walk (the Big Room loop), went back up and had dinner and watched the flight.  Apparently there are about 500,000 bats and it takes several hours for them all to leave the cave at dusk. They exit in a counter-clockwise spiral (no one knows why) that seems never ending and then form groups that fly off to look for water at either the Black or the Pecos Rivers. It was a beautiful fall evening in NM and they were quite breathtaking against the sky with the colors at dusk. One is not allowed to take any pictures of them exiting so Bob could only take something after we walked away from the viewing area.