Layered and cruising at a bone-chilling 10 below

GREENVILLE, Maine -- From the cove near the town's only traffic light (blinking yellow), the frozen expanse of Maine's largest lake stretches 40 miles to the opposite shore. Jutting from the ice, a dock tilts against the bank in the foreground, as if slammed there by a wave and frozen on the spot.

Shuttered cottages line the cove, which bustles in summer with powerboats and floatplanes. But today, only the occasional snowmobile whizzes along the ice, following a trail marked by the skeletal remains of Christmas trees, their needles plucked by wind. Beyond, ice-fishing shacks dot the lake's surface like scattered building blocks.

When the motel desk clerk hears our plan to spend the next day exploring the lake by snowmobile, he cocks his head at the thermometer on the facing wall: At sunset, it's 18 degrees below zero, with a wind chill of 37 below.

''Well, you should have your pick of machines," he says. ''Nobody wants to go out in weather like this."

It seemed like a good idea in the fall: cruising around Moosehead Lake's dozens of bays and islands at a time of year when few souls would compete for the right of way. That was before looking at a map and noticing that Moosehead is north of Montreal.

A banshee wind screams all night. Morning brings dazzling sun and pale blue skies, and merciful gods have calmed the wind. But it's still 10 below. We layer up: longjohns top and bottom, ultra-heavy hiking socks and insulated boots, padded nylon ski pants, light fleece top, heavy parka, balaclava, polypropylene gloves under heavy mittens.

At 8:30 a.m., Pat Gruenberg at Northwoods Outfitters, where we have reserved our ''sled," ticks off a safety checklist, stressing how easy it is to get lost (''The lake is like a big desert.") and how hard it is to hear other approaching snowmobiles through padded helmets (''You have to look around constantly.").

Not surprisingly, novices like us get into more than their share of accidents, usually because they transfer their excitement to the throttle and lose control of the sled. Or they smack into a pressure ridge, a rupture in the ice caused by warming and freezing. A ridge can form a ramp, sending a sled flying into the air. Or it may loom as an all-but-invisible-until-it's-too-late wall of ice. Or conceal a watery crevasse beyond a harmless-looking bump.

''Another thing," continues Pat, who also works as a trauma nurse at Eastern Maine Medical Center and knows the dangers of which she speaks, ''avoid riding too close to the shore or in narrow passages between islands where currents may cause thin ice."

We take a map, buy a compass, and figure out how to use them. Outside, a man named Mark lifts the hood of the two-seater Arctic Cat we'll be riding and tells us how to change the spark plugs in case they foul, which shouldn't happen unless we let the sled idle too long. The most important equipment on this adventure, it seems, is a large, steaming dollop of common sense.

Mark tells us the annual auto race will take place on the ice at Kelly's Cove at lunchtime, and suggests we have lunch at Kelly's Landing, ''where you can eat and watch the races."

Now, heads stuffed into helmets, it's time to hoist our padded legs over the frigid seat, turn the key, and go. We surge ahead, bumping across the frozen treadmarks of other snowmobiles. The sled noses north.

Off the rutted travel routes, the ride smooths out, save for occasional snowdrifts. Almost no one else is out yet on this part of the lake. Beyond the shelter of the cove, the wind has sculpted the snow into waves, and the brilliant light etches their contours. By about 9:30, the dazzling sun promises rising temperatures. Other snowmobiles begin to zip across the ice. In the lee of a cluster of tiny islands, a handful of ice fishermen -- not a woman in the bunch -- are busy loading gear into their shanties.

We continue toward the middle of the lake, where more islands hold cabins. The black-green spires of pine and spruce on the slopes are outlined in white.

Suddenly an enormous bird lifts off a pine snag on the island directly in front of us. Its wings flap as if in slow motion, and it takes a beat to realize that this creature is far larger than the other hawks and ospreys. The bird banks to the right and into the sun, where its head gleams against the viridian backdrop. We have witnessed a bald eagle in flight.

We pick up speed a bit, peaking at 40 miles per hour. Other sleds streak past doing at least 60. The appeal of the sport seems to be partly social, as many snowmobilers travel in small packs. Shortly before noon, cold has numbed our noses under the helmets, and we head back to Kelly's Landing for a hot lunch and a ringside view of the auto races on ice.

We park our sled amid a squadron of others. Inside, seated in a booth, we watch the first race begin. Like a scene out of ''The Road Warrior," a half-dozen ordinary cars skid and slew around a track of bare ice. After the first lap, the vehicles vanish into a cloud of powder, with only occasional flashes of fender breaking into view. Just as the snow settles, the crazy cars round the curve, raising the fine white mist all over again. It must be a long winter up here.

Juiced by the sight of the buzzing cars, a young snowmobiler starts jumping his sled over a snowbank close to the restaurant, out of the way of the race. He pops a wheelie, and no blowing snow obscures the view. He has stolen the show.

By the time we reach the shore we started from, it's almost 2, and the lake is alive with snowmobiles, sun flashing off hoods and helmets. One of us is reluctant to park the machine, knowing it's going to be a long time before we ride again. The other almost weeps with relief, hoping the next outing, if there is one, will be warmer.

Jane Roy Brown is a freelance writer in Western Massachusetts.