As the past-its-prime retired school bus churns slowly up the one-lane dirt track toward the put-in to West Virginia's Lower Gauley River, our driver, the owner and namesake of Rusty's Shuttle Service, keeps up a chatter on the radio to avoid the unpleasant surprise of two buses meeting on a blind corner flanked by sheer drops. Now, cresting an especially high and dicey bend, he shouts into the microphone with more than the usual gusto, "Rusty Rusty, top o' the world!"

Top of the world, indeed. Hundreds of feet below, framed by valley walls kissed with early fall foliage, lies the Gauley River, its rapids sparkling in the Indian summer sunshine like jewels on a string. In a steady stream, rafts, kayaks and the odd canoe pick their way through the top-flight rapids.

This is always a beautiful valley. And for whitewater buffs, it can be prime paddling all summer long. But for six glorious weeks in late summer and early autumn, the Gauley jumps from pleasant to perfection. That's when the Army Corps of Engineers releases the perfect doses of pent-up river from the Summersville Dam just upstream, awakening the Gauley's world-class rapids at a time of year when most other rivers dry to mere trickles.

"It's like a ski area having the best snow in the world, when nobody else even has snow," says Jeff Proctor, co-owner of Class VI River Runners in nearby Lansing, W.Va. During "Gauley season" (Sept. 10 to Oct. 17 this year) river guides from Chile to Alaska make their pilgrimages to this whitewater mecca, drawn to what may be America's best one-day rafting adventure and the river culture that surrounds it.

The paying thrill-seekers are never far behind. The most adventurous of them sign on for the Upper Gauley, with no fewer than five Class V (extreme) rapids. The lower section is milder, if only by comparison, culminating in rapids aptly named Pure Screaming Hell. On both sections, clients -- and not just guides -- provide the paddle power needed to avoid mid-river boulders and smash-through waves. But no one leaves hungry, as raft companies strive to outdo one another with gourmet riverside lunches. Some outfitters run elaborate camps with cushy cabin camping and a host of apres-paddle activities including restaurants, hot tubs and endless video replays of that day's whitewater action.

The rapids are always the top draw, but one weekend every Gauley season, the world's biggest whitewater party does its best to upstage the river itself. This year it's Sept. 24-26, and rafters and kayakers, tie-dyed old-schoolers and tongue-studded Gen-X daredevils will all rally at the annual Gauley River Festival, universally known as Gauley Fest, to celebrate their shared love of fast-flowing rivers and anything-goes bonhomie.

The masses fill the Nicholas County Veterans Memorial Park in Summersville, W.Va., with thousands of mud-spattered vehicles bearing brightly colored kayaks. Amid the labyrinth of bumpers in the parking area sprout tent cities, patches of tortured earth with the warmth of home, thanks to folding chairs and the banter of old friends.

Past a gate guarded (if that's the right word) by a rangy volunteer with a gray ponytail and a guide's deep tan lies an amalgam of trade show, state fair and bluegrass festival, all sliding deeper into good-natured anarchy as the night progresses.

The Gauley festival began in 1983 to celebrate the cancellation of a hydroelectric project that would have disrupted recreational access to the river. Now the festival raises hundreds of thousands of dollars each year for the advocacy group American Whitewater, which uses the money to protect and improve access to rivers around the country.

The revelers are mostly river buffs, augmented by a few in-the-know locals and professional festival followers. Alcohol isn't sold on the premises, but almost everyone seems to plan ahead. The crowd on land mirrors the one on the river: clutches of river-running friends, mostly men between 20 and 50 years old, but otherwise defying demographic pigeonholing.

Recent Gauley Fests have drawn more than 6,000 people and contributed nearly 10 percent of American Whitewater's annual budget. The sound track is alternately speed-metal and country fiddle. In the dust raised by thousands of water-sandaled feet, more than 100 vendors' booths speckle the fairground. Video monitors loop whitewater acrobatics and the more popular heart-stopping disaster footage boaters call "carnage."

"The Spam-eating contest was a big hit last year, and one year we had pig wrestling," says American Whitewater's Michael Phelan. "We had to pull the plug on that. It was an animal-rights-type thing."

This year there's talk of a no-holds-barred dodge ball tournament. That may be enough, because usually a day on the river leaves even the adrenaline-addicted Gauley Fest crowd satiated.

Last year, after cruising the lower river in my kayak, I decide to tackle the more challenging upper section in a raft. This is the ultimate in commercial raft trips, wild enough that most companies enforce a minimum age of 16. (Paddlers as young as 12 are welcome on the Lower Gauley, and kids as young as 6 can raft the nearby New River.) Outfitters nonetheless boast an impressive safety record, perhaps because only the best guides get the plum assignments. And those keep coming back for more, such as Glenn Goodrich, who hasn't missed a Gauley season in 28 years. "Two things make a world-class river -- volume and technicality," says the veteran guide. "A lot of rivers have one or the other, but the Gauley is a classic combination of both."

I thought of that as my raft drifted toward Pillow Rock, where the river runs full-force ("volume") into a house-size boulder that has to be sidestepped ("technicality"). From up close it resembles the killer wave in "The Perfect Storm."

Rafting companies deploy a man atop the boulder with a rope to drag ejected rafters to shore, and a dozen others -- mostly hot-shot kayakers who run this river many times each fall -- congregate like vultures, eating their lunches and enjoying the carnage. There's plenty of it. Kayakers flip with regularity, only to pop back up with an Eskimo roll.

Rafts also lose passengers; occasionally a whole raft-load will go over. Despite its fearsome appearance, Pillow Rock is a relatively safe place for an unintentional swim, and guides gather dismounted passengers in the calm water below with an ease bred of long practice. Our guide, Mike Hanford, says we've already survived the most dangerous part of our Gauley trip -- the drive.

That doesn't calm the tingling in the pit of my stomach when Hanford announces his plan to take the "splat line," meaning he'll drive our seven-person raft straight down the fastest tongue of current and into the roaring whitewater. If we're lucky, and our guide is as good as he claims, we'll come close enough to tap the boulder with our paddles and our raft will balance on the edge for a giddy moment, then skid safely into the eddy below.

"This is no Disney ride," he shouts above the roar of the current as it grips us and flings us toward Pillow Rock. We slam into the pillow, teetering sideways to manic shouts of "High side! High side!" -- our cue to throw our weight to the side of the raft rising inexorably on that churning pile of foam. The three of us on the low side stretch to the high side and the raft begins to stabilize. In an instant of clarity I realize we're going to make it -- and I reach with my paddle for the rock. My friends do the same, clattering an uneven victory salvo on the suddenly less-menacing face of Pillow Rock. Now we'll have something to talk about at the Gauley Fest.

Many rafters say West Virginia's Gauley River dam releases create the best one-day ride in the country. Below, the annual Gauley Fest attracts a crowd.