Peter Davis is 29, from England, on a business trip here. Yesterday, while strolling across Key Bridge, he glanced over the railing at the Potomac River below and saw the wide stretch of water, the red and silver canoes, and the opportunity to acquire a tan.

"It was a nice, sunny day and I couldn't think of a better thing to do," he said. So, Davis, who works for a British development firm, rented a battered red canoe at Jack's Boats on K Street, loaded on a steak sub and a beer or two and set off downstream to discover the Potomac.

By early afternoon as the temperature climbed to 80, he lay in the sun on a sandy and vine-tangled Roosevelt Island beach, his shirt off, smoking a cigarette, watching the river flow by. Only the roar of the overhead jets, and the faraway whine of the traffic, gave clues that his was an urban adventure.

"It's beautiful," he said. "I went down one of the creeks and there were some terrapins, and a few trees had been felled by beaver. And I found a small, dead snake." Nature in the raw, despite the nearest port of call being the massive white and brass of the Kennedy Center.

For many who took to the water yesterday, the Potomac River was at its most sublime. To be sure, there was the usual debris awash in the tide -- a plastic chicken livers container, rusty Schlitz cans, a soggy houndstooth-checked cap. Birds were not in evidence, either, except for a lone mallard, a few gulls and bridge pigeons. But the river smelled clean, the breeze was gentle, and the sun warm.

Arlene Alligood, 48, a publications consultant from the District, was there, yellow sweatband around her head, and rowing an Alden shell. "I'm addicted to rowing shells," she said. "It's similar to being born again. Once you start this stuff, you're hooked. I want to try to do it every morning."

Her favorite way to spend a Sunday is to collect copies of The Washington Post and The New York Times and bring them to the Harry T. Thompson Boat Center near the Watergate, where she stores her shell. "I drink coffee and [eat] croissants, yuppie-like, and I row a little now and then, and pretend I'm getting some exercise. It's wonderful."

Her only regret is that more people aren't able to discover the joys of rowing, which she says is because of the shortage of riverside boat storage. "The city should do something," she said, and rowed away, heading for Key Bridge.

Motoring slowly, very slowly, along the river was Daryl Friedman, 22, in an 8-foot inflatable Electra Sport dinghy. "It was between doing this, and writing my paper for American University," he said. "I heard the weather report, and this just sounded like a better idea." Friedman, a graduate student who also works in the press office at Wolf Trap Farm Park, was on his way home from a cruise by the Lincoln Memorial.

A tour boat, with a "Spirit of 76" sign, passed, windows open to the breeze. And powerboats, including One Life and Storm Along. A Hawaiian Punch can came by.

Wes Case, 41, the managing director of pulmonary and critical care medicine at the Washington Hospital Center, came by in his sport canoe, a bottle of Coppertone and a can of Diet Rite at his feet.

Case said he does a lot of boating on the upper Potomac, but that this was his first trip on the lower river. "I wanted to see a lot of buildings -- the Monument and the Kennedy Center -- from the water." So far, he had no complaints, except for the fast powerboats. "If it weren't for all these hot-rodders, I'd really enjoy it."

Pink and orange sails filled the river between the Memorial and 14th Street bridges, where 40 people took part in the 3rd Annual Potomac Cup Board Sailing Regatta. "Really light wind," said James Jacob, 29, a stockbroker from Alexandria, who had just placed third in the advanced division. "It's reasonably frustrating sailing. I did fine, but there are a lot of glassy spots."

Watching the racers from aboard a powerboat, the Polly Wog, was a visiting couple from Atlanta, Dr. and Mrs. John Purcell. Purcell said he was in town to attend an American Psychiatric Association meeting at the Washington Convention Center, but had been persuaded to join a family outing on the river. "We kidnaped him," said one of Purcell's hosts.

On a board but not in the regatta was Bob Zimmerman, 47, a State Department desk officer for Egyptian affairs, who was related to the crew of the Polly Wog. Zimmerman spent at least part of yesterday in a checkered bathing suit, grappling with shifting winds and the whims of his Mistral Maui board.

He lost control and fell into the river. "Come on in -- the water's fine," he waved to the Polly Wog. Zimmerman said he planned to sail every weekend from now on. "I'm also thinking about taking my board and launching it during lunch hour." Finally, he righted his board, positioned his feet, and sailed off in the direction of the Pentagon. "How could this be any better?" he asked.