WAMPUM, Pa. -- Blame it on my (middle) age or the fact I'm a girl. But the males in my family had a pretty strong reaction when I told them I had plans to spend the day riding an all-terrain vehicle in this tiny Lawrence County town -- namely, they said I was crazy.

"Geez," my husband said, rolling his eyes. "What's next? A hand-grenade juggling class?"

When I let it drop that the outing at 600-acre Mines & Meadows ATV Riding Resort would include four-wheeled spelunking through an abandoned limestone mine, well, the boys got even more distressed.

"Haven't you seen 'The Descent,' " my oldest son asked, referring to the 2005 horror flick about a caving expedition in the Appalachian Mountains that goes horribly, horribly wrong.

My 15-year-old minced even fewer words. "Mom!" he exclaimed. "Don't die!"

Who could have blamed me, then, if my heart was racing as I inched my cherry-red Kawasaki Praire 360 4x4 across the concrete parking lot and into the woods on a drizzly Tuesday? My guides had sufficiently schooled me on how to drive the 640-pound machine, of course, and my head was safely cocooned in a duck-billed helmet fitted with thick goggles.

The object of our ATV desire, the mines, were more than 2 miles away, and while most of the trails were clear of low-hanging branches, they were rife with muddy ruts and deep, mucky puddles of rain water. Almost immediately I had to make a decision: Do I ride in the established wheel tracks and chance getting stuck, or turn the tires slightly uphill toward the solid terrain on either side and hope I didn't tip over?

Turns out, either option would have been OK. ATVs, I happily discovered, make short work of mud, rocks and uphill climbs, thanks to powerful four-wheel drive. As far as tipping over, all I had to do was adjust my weight slightly to the side to balance the ride. Maybe I could do this after all!

We've all heard the stories about riders ending up in the ER -- or worse -- during an off-road adventure. Just three days before I took my maiden ride, former U.S. Congressman Bill Orton (D-Utah) was killed when his ATV flipped over on a sand dune at Little Sahara Recreation Area in Salt Lake City.

Yet most of those fatalities, fellow rider John Prusak was quick to explain, are caused when people drive too fast, horse around on trails or don't wear proper safety equipment. Or, he says, they choose an ATV that's too big and powerful for them.

As publisher and editorial director of 'ATV Magazine" and 'ATV Sport," Prusak might be a little biased. Then again, one could argue he understands these machines and the adventures riders have on them better than most -- his magazine enjoys the largest circulation (215,000-plus households) in the sport. At any rate, it's unlikely I'll get anywhere near my Kawasaki's top speed of 40 mph. That's better left to the throttle jockeys in front of me, who patiently wait for us ATV grannies to catch up when we fall too far behind the pack.

Critics decry ATVs as noisy, polluting machines that disturb the peace and chew up property, particularly public lands and wetlands. But ranchers, farmers and others who have to negotiate tough terrain to get their jobs done have long appreciated the fact that no trail is too steep, rocky or hard to climb with an ATV. And now, more recreational riders than ever know it, too. Some 15 million Americans ride all-terrain vehicles, according to the ATV Safety Institute, with 70 percent of those riding as a family activity. And a growing number of them (currently 10 percent) are women.

ATVing is especially popular in Pennsylvania. In 2008, more than 18,800 new all-terrain vehicles were sold in the state, making it third in the country behind only Texas and California, said Prusak.

Given the sport's popularity, more than a few commercial ATV riding parks have sprung up in Western Pennsylvania in recent years. What sets Mines & Meadows apart from the competition -- besides 45 miles of trails of varying degrees of difficulty on 600 private acres -- is the underground riding through pitch-black limestone mines dating to the late 1800s. It's unique enough that Prusak traveled all the way from Minnesota to Lawrence County to ride and write about it.

Now in its third season, Mines & Meadows is the brainchild of Beaver County developer Bob Svihra. A few years ago, the 70-something entrepreneur was out riding with friends when they happened upon a 400-acre property up for sale. Like a lot of recreational riders, Svihra had begun to notice there were fewer and fewer places for people to ride ATVs without damaging someone's property. Riding across this vast piece of land, something clicked.

"I thought, 'What a great place for a resort,' " Svihra said.

So great, he bought it.

Not long after, Svihra realized his purchase sat adjacent to land owned by the Underland Development Corporation, an underground storage facility for boats, RVs and other large vehicles. Included on that 65-acre property was an old limestone mine that had been worked by the Crescent Cement Company from about 1890 to the 1920s.

"And I put 2 and 2 together," said Svihra. "Why not have riding on trails and underground?"

Underland's owner Steve Grinnen thought it was a good idea, too, and agreed to lease a 14-acre undeveloped portion of the mine to his neighbor for underground rides. Eventually, Svihra would add 200 more acres to the park.

Being a complete novice, I wasn't sure what to expect once we hit the winding woodland trails, other than I was going to get dirty. Really, really dirty. The more ground I covered, though, the more I began to enjoy it. Within just a few minutes, I was comfortable enough behind the throttle that I was silently cursing the slow-poke driver in front of me. Seriously, couldn't the scaredy cat speed it up just a little?

It would take our group of six, riding in line, almost a half hour to reach the cave. But what a fun half hour. We splashed through puddles, zoomed up hills and crunched across rocks. It almost made me forget about the hundreds of bats that surely awaited us upon entering the underground mine. But not to worry, Grinnen assured me the furry winged rodents most likely had already fled their subterranean home. Most likely.

Once we squeezed our ATVs through the narrow log opening leading into the pitch-black mine, I had a scarier thought. The only thing lighting the way in the absolute darkness was our ATV headlights. So while we could see where we were going as we traveled 150 feet underground, we couldn't see what was to the sides or behind the last vehicle. It was a feeling so creepy that I was sure Golum himself might pop out from behind the limestone walls, if not one of the "crawlers" who stalked those unfortunate hikers in "The Descent."

We slowly zoomed our way through the eerie, 50-degree darkness, splashing through puddles, curious (or afraid?) of what might lie around the next dark corner. Then we hit it: a hidden 2-acre underground lake. We spent the next half hour taking turns driving through the shallowest water with our feet up near the handlebars.

Before long, it was time to head back to the visitor's center for lunch. As we rolled toward daylight, we passed the 14 pitch-black "growing rooms" in which the Sno-Top company cultivated mushrooms in the 1980s and '90s. At the height of production, the rooms provided 6,000 square feet of subterranean growing space. Today, they sit off to the side in the darkness like forgotten tombs.

After a quick lunch of pizza in Svrihra's office, we headed back out into the trails. The more experienced riders spent the afternoon testing their skills on steep rock and hill climbs deep in the woods, or catching air on ATV jumps.

I stuck to the easy main trail under the power lines. I like to have fun, but despite my family's suspicions I'm not crazy. Some things are best left to the experts.