The Canadian Rockies were snowcapped and stone cold above us. The Athabasca River was pounding past in a steep, wide rush of rapids that sounded like a freight train clanking through a tunnel. Pat Leonard, looking every bit the clear-eyed wilderness explorer, peered down the river and wondered if our canoes would actually float.

"It would be a little embarrassing after all this work to sink right here," said Leonard, a 46-year-old physicist from Maryland, trim as a gymnast, stronger than dirt and, at the moment, up to his elbows in granola, brown rice and cheese. "I think I'd go down with the ship."

As summer adventures go, this 2 1/2-month trek across northwest Canada, on remote waterways that have changed little since voyageurs trapped beaver here 200 years ago, promises to be breathtaking in every way.

Our leader, 38-year-old Donna Berglund, who lives with Leonard in Germantown during the two months each year she is not camping beside some North American river, has said she expects no more than 10 hours or 63 miles of paddling each day.

Of course, if we are attacked by bears, swamped by rapids or carried off by the indigenous mosquitoes that are rumored to resemble sparrows armed with swords, we may have to canoe a bit more to make up lost time.

"If we don't get to Hudson Bay before freeze-up, there is no place else to go," said Berglund, who represented the United States as a down river kayaker in the 1975 and 1977 World Championships. Since earning a doctorate in chemistry at 24, Berglund has taught general science, geology, canoeing and outdoor survival skills at three colleges and for Outward Bound. She has also logged more than 18,000 miles by canoe in the last 15 years, including one 2,486-mile trip she led through Canada in 1980.

Berglund's long brown hair is usually pinned under a cap, her features are soft and her skin pale. She has a very easy laugh and a way of looking at you that is uncommonly transparent and direct.

She also has a strong enough reputation to persuade manufacturers to donate or lend almost every piece of equipment needed by the seven people on this trip, from canoes, sleeping bags, tents and hiking boots to surplus food--even plastic bags.

"We'll give this equipment more wear in one trip than most people would in a lifetime," said Berglund, explaining the economics of the equipment deal in terms that sounded a bit ominous.

Berglund had less trouble finding free equipment than she did tripmates who had three free months, adequate experience and a sense of adventure great enough to risk health and sanity in territory where grizzlies and polar bears roam and rescue in an emergency might be 15 days away.

"Most of us don't know each other at all, but there is some comfort in knowing we all share a love of wilderness and have at least a few screws loose to want to do this," said Leonard, who seems at this early stage to be an overaged Eagle Scout, the kind of man who keeps his socks color coded and trims his beard every morning. He is a mountain climber, a kayaker and a story teller with an apparently endless supply of anecdotes.

The oldest member of the group is Dick Sears, who is 52 and looks older with his gray-streaked beard. Sears cashed in a career as a salesman and buyer for department stores a few years ago and now makes $5,000 annually patrolling a ski slope in Minnesota. He is 5 foot 5, with round shoulders and 30 years experience paddling flatwater lakes in Minnesota and Ontario. He met Berglund during an Outward Bound course and was impressed. It took only six months to talk himself into joining the group.

"I may be too old and weak for this trip. But if I didn't at least try, I would always wonder if I could have," said Sears.

The other couple on this trip is Don Rabern, a 26-year-old skier, kayaker and structural engineer from Utah, and Marvel Harrison, also 26, a nutritionist, runner, kayaker and the only Canadian in the group. The timing of the trip was right for Harrison and Rabern, who met a few months ago while skiing. She finished work for her master's degree last week and he begins a job in September at Los Alamos.

Kate Finkbeiner is 20 and looks about 16. During the three days of packing food and gear for the trip, Finkbeiner, a senior at the College of Wooster in Ohio, has already shown a talent for organization and an abundance of freckle-faced cheer. But at 5-5 and 115 pounds, the trip seems to be terribly tough for her, considering canoes and 90-pound packs on portages will need to be carried over miles of dense and hilly terrain.

The youngest member of the group is 18-year-old Barry Crouch of Mount Ranier, Md. Crouch is 6-3 and 180 pounds, but has almost no experience in camping or canoeing. Since graduating from Northwestern High School, Crouch has been working as a gas station attendant and trying to write books about medieval warfare, magic swords and goblins.

He heard about the trip through Leonard's daughter and was invited to come despite his lack of experience because, as Berglund put it, "he's strong and we needed another person."

The group, including this 34-year-old reporter who is paddling the first 680 miles, represents a wide range of ages, experience and expectations. As we prepared to set off, there was a forced jollity that did little to mask obvious fears. Which of us would fail the pace? What flaws in our personalities would be laid bare by the forced communion we would share on this trip?

"One thing I've learned on these trips, you can't hide who you really are from other people. And you especially can't fool yourself," said Berglund, standing on the river bank in a pink flush of wild roses. "If nothing else, most people learn to be more honest."

With honest feelings of fear, we snapped the vinyl covers over canoes packed with hundreds of pounds of food, clothing and camping gear, squeezed ourselves into our alloted holes and made our first, most important discovery. We did indeed float.

"From here on it's all downhill," cried Pat as he pointed the nose of his canoe into the torrent of melted snow.

"That's right," called Don from from the bow of the boat. "Except for the 170 miles we still have to paddle upstream."

Next: keep your eyes open.