Mammoth, in Depth

Several caves around the country offer such tours, and I had taken an earlier -- and much easier -- one in Arkansas a year before visiting Mammoth. Both were fun, and they probably qualified me as a spelunker. But not as a caver.

"Cavers" are a relatively small group of skilled adventurers, somewhat akin to serious mountain climbers, though not nearly as celebrated. They explore the most remote parts of caves, sometimes mapping what they find.

Spelunkers?

"Cavers rescue spelunkers," smirked Kevin Neff, our wry 62-year-old guide.

My group of five -- Bella stayed behind in a kennel -- included no one better than a spelunker. Still, Neff knew we hadn't come to dodder along the tourist trail. Just after entering the cave, he gave us a moment to adjust our hard hats and strap on our kneepads. Then he looked down his nose and feigned a cave connoisseur's disdain for us dilettantes.

"I'm assuming you're ready," he said dryly. "Because we're leaving."

The crawling began almost immediately. As we veered off the main tourist trail, the shrinking passages forced us to our knees. Our hands smacked the clammy cave floor, then sank into soft powder and finally clawed at the edges of the Bare Hole, the tiny cataract where I had to exhale.

This was a test, Neff explained. Although we could all physically fit through the hole (people with chest or hip measurements larger than 42 inches cannot take the tour), the squeeze is more than some people can stomach mentally. Closet claustrophobics will be outed.

But we all passed, and the tour continued in a blur of crawling. I lurched and gasped through pass-ages with names like Birth Canal, all while listening to the nonstop monologue of the man behind me, who repeated things like "That was easy!" and "Piece o' cake! Piece o' cake! "

I crawl like an ostrich, so I was pleased that the second half of the tour involved upright walking, as well as a bit of free climbing down tall crevices and cave walls. The highlight, though, came when Neff began to make eerie "Star Trek"-style "oohing" noises, which disappeared into the vastness of a room called Cathedral Domes.

Here, the cave's ceiling soared some 100 feet above our heads, forming a vaulted chamber maybe 40 yards long. The white light of our headlamps sliced through the blackness to the ceiling, lighting the clouds of our breath as they drifted upward.

Eventually, though, the passageways shrank and, alas, crawling resumed.