Here is a place where young women in bikinis cluster around a 20-foot waterfall, laughing. When the sun beats down hot, they tiptoe across the rocks and plunge into the cool, cascading water, and the young men follow.
Here is a place where daredevil boys climb a sycamore tree, grab a long rope and swing out over a deep cool pool in a great wide river. When they reach the apex they let go, howling and flailing, and drop 15 feet into the water.
Here is a place where an osprey soars over treetops, then flaps its wings, "stilling" over some small fish visible in the water. It dives like the boy on the rope, straight down, and emerges with a silver perch in its talons.
Here is a place where 16 Canada geese, including six goslings almost fully grown, paddle about in a still pool. When the kayak draws near, they climb onto the bank and feed on new grass shoots.
A hen mallard flushes at the sound of approaching voices, then settles down 100 yards upriver among rocks.
A snake pokes its head out of cracks between boulders, then retreats. Here is a place where in the spring tom turkeys sometimes gobble, seeking hens to mate with.
Deer and raccoon tracks lead down to the river. Long, quiet pools end in cascading rapids. The canoe clangs over the rocks, and the standing waves wash over the gunwales. The young people whoop and lift their paddles overhead, flushed with fulfillment at navigating a falls called Stubblefield, or Yellow, or Difficult Run or Wet Bottom Chute.
Here is the Potomac, just north of the Beltway.
It's a place that in its ageless, architectural magnificence makes the Cabin John Beltway Bridge look like a tinker toy. In time, bridge will crumble and fall. Not the river. Not the gorge.
No one has figures on the numbers of people who recently have discovered the incredible wilderness stretch of the Potomac betwen Great Falls and Little Falls.
But every old hand on the river agrees the pace is astounding.
"If you just passed by and looked at the parking lot you'd say 'Oh, my God,'" said John Seabury Thomson, who wrote a book about this piece of water.
"But if you look closer, you find out that the parking lot is the only place it's crowded. Once you're on the water you have all the space you need. It's a big river."
Last weekend the parking lot on MacArthur Boulevard across from Old Anglers Inn looked like Friday evening on the Long Island Expressway. From the cars emerged kayakers, canoeists, fisherman, rafters, all working their way down the hillside to the C & O Canal and the river.
At the canal fishermen and women stretched upstream toward Widewater and downstream too. A canoeist hoisted his boat off his head long enough to ask a woman, "What's on the stringer?"
She lifted a chain out of the water, and with it a smallmouth bass about 13 inches long.
"You caught that here in the canal?" he said.
Thomson is right. The crammed parking lot full of steming cars is the last sign of a crowd. Unlike Ocean City, where you bounce from one jam to another, the river is too big to be overwhemed.
A picnic on the beach on the Maryland shore near Offutt Island, a 10-minute paddle from Old Anglers. There's only the sound of whitewater rushing over the rocks. Here is an eddy off the channel. You step in. Whoops. Deep water, over your head. But it's slack water here. No current. No danger.
Some kayakers come through from the only commercial outfit using the lower river: Washington Whitewater, which runs classes for beginners and novices six days a week.
Mike May is the instructor. He looks great.
"Do you ever worry about the quality of this water?" he is asked.
"I'm in it every day but Thursday, all summer long," May says, rolling the kayak on its side and ducking his head under water for emphasis.
Paul Eastman, executive director of the Interstate Commission on the Potomac River Basin, says as far as he knows there has never been any ordinance prohibiting full-water contact sports on the Potomac above the District line.
But until four or five years ago, the reputation of the Potomac as a polluted stream was bad enough that folks generally stayed off it.
Those billions of dollars the government and private industry have spent to clean up urban rivers must be paying off.
In every quiet cove and eddy for four miles down the river, boaters or hikers are cooling off in the Potomac.
They are present in hordes at Scott's Run at the foot of Dranesville Park on the Virginia shore.
That's where the girls in bikinis are playing in the waterfall. The water at the falls is cool, cooler than the water in the main river.
It's where the daredevil boys are swinging off the trees on a rope.
You ease out of the cove in your canoe. The water picks up speed. You are sweeping between boulders. You hear the rumble of the whitewater ahead. You pick your spot and, in the phrase so popular in adventure sports, you go for it.
The canoe rocks in the standing waves and races through the chute Water splashes over the sides. You paddle like mad.
You made it.
And up ahead, the ultimate incongruity lurches into view: the Beltway Bridge.
A few factors save the Potomac above Washington from people overkill.
It is not a thoroughly easy place to reach. The National Park Service owns the land on the Maryland shore, and the Virginia shore is protected from development by public ownership and scenic easement.
To get there you have to walk across rocks or down muddy slopes or on paths through the woods. There are no first-aid stations or hot dog stands or laces to buy cigarets.
It's an unpredictable place. There are snakes in the rocks, though almost all are harmless. Sometimes after hard rains the water sweeps up out of its banks, muddy, fast and dangerous.
To do anything on the river besides fish from the banks or picnic, you need a boat -- a canoe, kayak or rubber raft. And you have to know how to use it.
"It's beautiful, spectacular and fundamentally easy," said Thomson. Not completely easy, though.
The Canoe Cruisers Association recommends that anyone trying to shoot the Potomac between Great Falls and Little Falls should have experience on Class 3 rapids.
That's fairly rough water, but CCA whitewater instructors and Washington Whitewater's kayak teachers both use the heaviest rapids on the Potomac to teach beginners.
The point is that it is safe if you know what you are doing if you are with someone who does.
It's the element of danger, and the fact rivers aren't easy places to make one's way around has kept the Potomac from overpopulation.
But times are changing fast.
"Don't write that story," whispered a fellow who heard that the river was getting feature treatment. "It's a secret."
But from a look at the Old Anglers parking lot and the one at Great Falls, the cat is already out of the bag.