As in an Old West movie when a gunfighter reaches for his holster, someone twitches a throttle and chaos breaks out at the starting line. The riders, mostly in their teens and 20s, begin racing uphill. Plumes of sand fly out in giant rooster tails from their rear tires.

They don't call this 200-foot-high dune Show Off Hill for nothing.

On a city street, these riders would be busted by the cops -- not only for their antics, but also because some are too young to drive. But riders of all ages, as long as they are accompanied by an adult, are welcome on the dunes, where drag-racing is good clean fun.

No one seems to care who gets to the top first. After a few victory cheers and a lot of smiles, they all turn around and head back down to race again. And again . . . and again . . . and again.

Show Off Hill is the first sand that off-road riders see when driving out of the Willamette Valley for a weekend of play on the Oregon Dunes.

The cacophony from their noisy machines -- quads, dirt bikes, Jeeps and rails (an open dune buggy encased with steel bars to protect passengers during a rollover) -- mixes with the adrenaline rush of competition to produce an almost palpable high-octane high.

One rider on a powerful home-tinkered machine gives the others a half-hill head start but still beats them to the top. Everyone laughs when he pops a wheelie and falls off the back.

One quad sits forlornly to the side. Without some serious mechanical assistance, it won't be running any more this day. Donna Zimmerman of Scio stands nearby. She and her two teenage boys have come to the largest coastal sand dunes in the country to ride with 30 family members and friends. She brought along three "bikes," slang for four-wheel ATVs.

"They broke it," says Zimmerman, nodding at her boys but not appearing too concerned. "That's the way it goes. The bike that breaks ends up being my bike for the day."

Another member of her group, Jim Namitz of Albany, never leaves riding time to chance. He and his wife, Julie, bring six bikes, even though they have only two teenagers.

"They're always bringing some of their buddies along," says Namitz, whose biweekly summer trips to the dunes coincide with payday.

Parents say that ATV riding teaches their kids responsibility. The Namitz youngsters, for example, will spend Sunday evening cleaning and lubing six bikes, while the Zimmerman boys learn to repair small engines.

But that's not the only reason these families got into ATVing. How many other activities do independent-minded teenagers look forward so eagerly to doing with their parents?

The drag races and big jumps on Show Off Hill are a tiny part of ATV activity on the dunes, where more than 20 square miles -- about 40 percent of the total dunes area -- is open for riding.

Motorists speeding past on U.S. 101 have no inkling about this vast expanse, unless they hop aboard a dune buggy or take an arduous hike in the sand. About 400,000 ATV riders a year visit the dunes, about as many who ski and snowboard each winter at Mt. Hood Meadows Ski Resort.

The gas they buy, the meals they eat, the motel and campground bills they pay are a jolt for the tourist-dependent economy of Florence and its 7,263 residents.

Visitors who don't own something to ride can buy a dunes tour or rent a dune buggy. An hour's tour in an old school bus, stripped to its chassis, goes for $10 a head. Rental quads can give a sample of ATV fun, but at $40 per hour they get expensive.

Which is why, after a few rentals, a family must decide whether to buy its own dune buggies.

The answer was a resounding yes for the Esmay family of Canby. Justin and Tami Esmay spent $11,000 for two quads, $200 for rear sand-paddle tires, $450 for three helmets and a few hundred on the hot clothing line by Fox Racing.

The large upfront cost is offset by a low operating cost -- about $15 in gas for five hours on two machines.

Riley, the couple's 2-year-old boy, danced jigs in the parking lot at Goodpasture staging area, a trail-riding spot next to Show Off Hill.

"He has his own battery-operated four-wheeler at home, so he knows all about ATV riding," Tami said as she cornered him to place a full-protection helmet over his head.

She unfurls a harness and snugly binds her youngster to her chest. There will be no drag-racing for mother or son -- only slow, scenic rides through the dunes or across wave-lapped coastal beaches.

Until Riley gets older.

Terry Richard: 503-221-8222 terryrichard@news.oregonian.com

TRIP TAB

An Oregon Dunes weekend (two nights) for a family of four:

Travel: 170 miles from Portland, 60 miles driving around Florence, $48 in gas

Overnight: $34 for a campsite at Honeyman State Park, $120 for a midrange motel room or $370 for the apartment suite at the Edwin K B&B

Dining: $60 for breakfasts, $40 for picnic lunches and $120 for dinners

Dune fun: $40 ($10 per person) for a scenic tour, $160 ($40 per person) for a quad rental for an hour, $5 for a Northwest Forest Pass

More fun: $24 for two sandboard rentals, $24 for two adult and two youth tickets to Sea Lion Caves

Total: Roughly, $555 if you camp (less if you bring food from home)

Beyond the dunes

Let's boogie (board)! Florence is full of action

There's much more to the Florence area than dunes and dune buggies. Here's a sampling of activities for all ages and interests:

OUT AND ABOUT

Beachcombing: The four-mile South Jetty Beach, south of the Siuslaw River, has six parking lots for foot access to the beach, which is closed to vehicles May through September. Heceta, Sutton and Baker beaches stretch seven miles north of the Siuslaw, where vehicles are prohibited.

Shopping: Old Town Florence has more than 60 shops and restaurants, including many galleries and specialty stores.

Fishing: Some of the state's best fishing for bass and other warm-water species is in large lakes south of Florence: Woahink, Siltcoos and Tahkenitch.

Golfing: Sandpines (541-997-1940) and Oregon Dunes (541-997-3232) are coastal links courses loved by golfers. Camp 101 (541-997-1590) is popular for families with its pitch-and-putt course and covered outdoor game hall.

Horseback riding: C&M Stables, seven miles north of Florence, offers beach and dune trail rides; 541-997-7540.

Scuba diving: Oregon's first underwater dive park is at Woahink Lake in Honeyman State Park. Check with Central Coast Water Sports, 19th Street and U.S. 101, 800-789-3483.

Stern-wheeler cruising: The 65-foot Westward Ho! paddles the Siuslaw River from Old Town; 541-997-9691, www.westward-ho.com.

DUNE TOURS

Sandland Adventures: A rental and tour company one mile south of Florence on U.S. 101, 541-997-8087, www.sandland.com, with go-karts, bumper boats, mini-golf

Sand Dunes Frontier: A rental and tour company four miles south of Florence on U.S. 101, 541-997-3544, www.sanddunesfrontier.com, with camping and mini golf

KIDS FUN

Rent a sandboard at Sand Master Park and ride it down a dune.

Grab a boogie board at Central Coast Watersports and head for the beach.

Rent a paddle boat at Honeyman Park Lodge on Cleawox Lake, a canoe at Central Coast Watersports for a trip down the Siltcoos River Canoe Trail or a Jet Ski for a spin on Woahink Lake.

Comb the beach for glass floats, either accidental arrivals or ones intentionally buried above high tide between Christmas and Easter by the Chamber of Commerce.

Head 11 miles north of Florence to see the Steller sea lions in Sea Lion Caves.

Drive up the North Fork of the Siuslaw River for a hike on the Pawn Old Growth Trail.

Cheer for the cobra lilies as they dine on insects, six miles north of town at Darlingtonia Botanical Wayside.

Drive 12 miles north of town for a lighthouse tour at Heceta Head.

AMENITIES

Lodging: Spending a lot of money on lodging is unnecessary, even difficult, in Florence. Top-end high-season rates begin at $60 to $90, with budget rooms beginning in the $30 range.

Two to consider: Driftwood Shores (the only oceanfront resort in Lane County), 800-422-5091, and Landmark Inn (hilltop setting overlooking Old Town), 800-822-7811.

Camping: Three miles south of Florence, Honeyman State Park, 541-997-3641; Lane County's Harbor Vista Park, at the north Siuslaw jetty, 541-997-5987; Driftwood II (ATVs allowed) and Waxmyrtle (no ATVs allowed), Oregon Dunes National Recreation Area, 541-271-3611; Port of Siuslaw RV Park and Marina, just upriver from Old Town, 541-997-3040; (camping rates range from $15 to $22 per night).

Dining: Options range from gourmet to fish 'n' chips. Don't miss Bliss' Route 101 Restaurant and Lounge, where you can grab a table inside a candy-apple-red Ford convertible and admire '50s auto memorabilia. Morgan's Country Kitchen, near the dunes, is where ATV riders flock for breakfast. In Old Town, head for the Bridgewater, in a 1901 building.  

Visitor info: Florence Area Chamber, 270 Highway 101 N., 800-524-4864, www.florencechamber.com.