Lawyer Paul Sailer scrambles over a fallen log, carefully negotiates slippery stepping stones across a small stream, pulls himself up a huge rock in the path and strides face forward into an icky cobweb.

Ah, wilderness.

Sailor loves it.

On any given weekend, he might be exploring isolated woodland trails, cycling little-traveled backroads, nosing his canoe onto a secluded island beach or tackling some of this country's most exciting whitewater rapids in his kayak.

All, he is eager to point out, within 15 minutes to an hour of Washington. For an East Coast city of its size, he says, the Nation's Capital is uniquely blessed with an abundance of "spectacularly beautiful areas. You don't have to go far for them in any direction. I doubt many cities have as many beautiful undeveloped places close by."

There is, for example, the awesome sight of the Great Falls of the Potomac River, as seen from the Virginia side, and Mather Gorge immediately downstream. To avoid the transistor-radio crowds at the Great Falls Park concession area, he says, seek out the less-populated cliff's edge trail leading south to view the cascading river in quiet.

"The farther away you get," he said, "the fewer people."

For real seclusion, he suggests a canoe trip among the islands that dot the Potomac, especially on the calmer "flat-water" areas above Great Falls.On at least one island, "I've seen deer it's so inaccessible."

To Sailer, 36, a husky, bushy-haired Harvard Law School grad whose clattering blue Honda is filled to overflowing with a backpack, thermos, canoe paddles and assorted sports gear, the Potomac is the scenic and recreational wonder of this region.

"Because the Potomac has been protected," he says, you can step out of your urban high rise to an out-of-doors adventure for a morning or an afternoon "without much difficulty or preparation." Or expense, since access to the Potomac is either free or only a park fee, and the fuel cost to get there is minimal.

"It's nice to be near a river, because it's always different as the seasons change and the water level changes. Cloudy days are nice. Twilight is nice."

Sailer, a consultant who conducts projects for business and government and who is writing a book about the life-insurance industry, moved to Washington eight years ago. Like many newcomers, he had no idea of the scope of the city's recreational resources. But, unlike some people he had encountered, he set out systematically to discover them.

He searched out bookstores for guides and maps, talked to local sports associations and explored on foot and by bike and boat.Along the way, he learned white-water canoeing and kayaking ("I saw them on the river from Great Falls," and deciced he should try it) and hiked much of the Potomac shoreline from Georgetown to Great Falls, 15 miles upriver, and beyond.

But not, by the way, he says, along the popular C&O Canal towpath, which he finds too crowded and, well, "dull." Instead, he seeks out little-used trails close to the water's edge.

Recently, he put together a 2 1/2-hour Open University class called "Nearby Wilderness," where, as a former student puts it, he provides "a great wealth of useful information" about the local out-of-doors scene. His students, he says, tend to fall into three categorie: Washington newcomers, indoors types venturing out for the first time and longtime dwellers here "who haven't explored nature much. They may how one aspect, like hiking, but not canoeing or kayaking."

He has, he says, become almost "compulsive" about gathering detailed information on the region's nature spots. "I'm aiming to make it comprehensive." Showing a favorite trail south of Great Falls to a reporter last week, he scoped up a large handful of free park maps to distribute to his next class.

"I love exploring," he says, and that rapidly becomes evident as he investigates every side path and overlook leading away from the two-mile Difficult Run Trail that parallels the edge of Mather Gorge. "There may be hundreds of people at Great Falls," he says, "but very few people know about this trail." On a beautiful dry, sunny Thursday morning, Sailer, the reporter and a photographer are by themselves.

Sailer's philosophy of hiking is not to cover great distances but "to stop and look at beautiful places." On this route, with its white-water views, there is more stopping than hiking.

Later, he leads the reporter along the shoreside trail above the falls, where the Potomac takes on a whole new character. In the backwater, it appears peaceful, almost like some sluggish Midwestern river going nowhere Slowly. Here, he plunges through dense undergrowth off the path to stick as close to the river as possible.

The trailing reporter, waving off attacking gnats, points out that the park brochure warns of poisonous copperhead snakes, but that does not dampen Sailer's enthusiasm. On a rock or in a glade, he finds isolated picnic spots by the water's edge. A surprised turtle plops into the water, a rabbit scurries out of sight, ducks glide by.

The sole intrusion in this spot just minutes from the Beltway: Overhead jets from National Airport.

Sailor's out-of-doors excursions, mostly with one or two friends, have left him unharmed, though years ago he lost his glasses when his kayak overturned and his wallet when he was dumped from a canoe. Now, he sayd, "I tie everything down."

Parts of the Potomac, he alerts his classes, can be as treacherous as they are beautiful. The river has claimed many lives over the years. For canoeists and kayakists, "Never paddle in any area without knowing the major hazards" -- among them Great Falls and Little Falls and its dam. "And don't paddle in flood waters."

He advises enrolling in boating lessons offered regularly by Canoe Cruisers Association of Greater Washington, D.C., from beginning to white-water experience levels.

Though the Potomac is favored, Sailor also covers another nearby attraction, the Patuxent River, and the more-distant state parks and Shenandoah National Park that can be visited in a day's outing.

He is, he says, always on the lookout for new trails or scenic spots, and he enjoys sharing the information. "Although, my friends have told me, 'Don't pubicize them too much.'"