Kartchner Caverns (Hwy. 90, Benson, 520/586-2283 for reservations, 520/586-4100 for information, www.azstateparks.com, daily 7:30 a.m.–6 p.m., free w/tour reservation, $5/vehicle up to two people, $2 each additional person over 14) were discovered in the early 1970s by two cave-loving University of Arizona students.

Gary Tenen and Randy Tufts knew right away that they had shimmied down a sinkhole in the Whetstone Mountains into caving immortality, as the small but “wet” cave—meaning that it is still forming drip by drip, in a very real sense “alive“—is one of the most spectacular water-on-rock formations of its kind. And yet the explorers managed to keep their find a secret for several years in an effort to protect it from cavers less responsible than themselves.

They called it Xanadu, after the great English poet Samuel Taylor Coleridge’s famous unfinished poem Kubla Kahn, a name given to the Throne Room’s 58-foot main column, formed not so much by drips but by torrents of water flowing into the cave over millennia, and the largest cave column in Arizona.

Eventually Tenen and Tufts told the property owners what they’d found, and the Kartchner family quickly joined those who wanted to see the cave preserved. A pre-tour film in the park’s Discovery Center tells the whole story and explains what makes this cave so unique. There’s also an interesting museum and a gift shop; just outside the Discovery Center a native-plant butterfly garden is worth a stroll.

There are two different tours you can take though the caverns. The Big Room Tour (1.5 hrs, $23 adult, $13 age 7–13, no children under 7) is offered only October 15–April 15—during the summer months a large colony of bats returns to the Big Room, as they have likely done for eons, to give birth to and rear their single pups. The Rotunda/Throne Room Tour (1.5 hrs, $19 adult, $10 age 7–13) is offered year-round and is more than enough to satisfy even the most discerning spelunker.

Because the cave is still “alive,” much is made of its conservation. Visitors are warned repeatedly not to touch any of the formations, and guides are not shy about telling kids to stand back and keep their hands to themselves. The tour information is very repetitive if you’ve just watched the pre-tour movie.

If a tour of the cave isn’t enough, the park offers campsites with electric hookups, water, a dump station, and restrooms with showers ($22).