This cave is located about 2 miles west of Rt. 307, a few miles south of Akumal.   Big signs for it on 307.  The road between 307 and the cave is dirt and a little bumpy, but a fun ride through thick jungle.  Cost on 1/2/09 was about $20US person.   The site is very organized and is nicely low impact on the environment.    A small guide center is present at the entrance, and the only other structure is an open air cafe at the end.   A tour guide (part of the entry fee) describes the tour, gives you hard hats, and then introduces you to about a dozen local snakes in cages, all looking healthy and the guide said they are changed out every month.   He then takes you into the cave.  Guide was very knowledgeable and worthy of a tip.  Cave tour has lots of stairs, requires bending over a few times because of low ceilings, and is very humid.   But the tour is well worth it, with multitudes of stalagmites and stalagtites, pockets of docile bats, and fig trees who roots extend through the cave ceiling.  At the end of the cave tour is a big pool, a cenote that never had the roof cave in.  Very picturesque.   Tour took about an hour.   The cave exits into a zoo-like setting with wild deer running about, and birds (toucans, parrots), spider monkeys, and peccaries in fenced in areas.   Again, nicely done, looks very humane.   The spider monkeys were just spectacular, you could get very close to the caged part of their living space, and they would just stare at you and "hang around".   They take your picture as you are entering the cave and offer a nice print of it at the end for about $7US.  This tour is pricey, but very high quality and suitable for anyone over the age of about 6 (they need to be able to walk on their own in a hot setting).   Looks like they were putting the finishing touches on some zip lines, too.