One of the nicer traits of July is an ebb of ambition. The days trail off in a haze of vacation plans and unfinished tasks. It is the perfect time to slip away unnoticed.

So on a recent morning, when I should have been busy doing something else, I made a reservation to rent a kayak, hopped in the car and headed to Patuxent River Park in Upper Marlboro. I planned to do nothing but paddle. However, after thrashing upstream near the park's headquarters for a short stretch, my plans for a miles-long journey unraveled into volitionless drifting above Jug Bay.

The padded, open cockpit of the Pungo kayak seemed to invite drowsiness. Soon enough I closed my eyes, disturbed only by carp breaching the water's surface for a gulp of air.

The Otter, the park's pontoon boat, motored past. Park naturalist Jean Tierney's voice floated across the water, detailing the river's rich history to a group of visiting day campers. One of them waved, said, "I took a picture of you," as if he had proof of my reduced aspirations.

I wasn't up to much, but I was surrounded by activity, past and present. Native Americans, tobacco farmers, soldiers, hunters, crabbers, anglers, recreational boaters and conservationists have traveled and worked this ever-changing river through the centuries. The park, which has grown to over 6,000 acres the past few decades, has gone to great lengths to preserve its land and water channels.

It also has responded to the needs of park visitors, most recently by increasing its fleet to eight rental kayaks to go with its platoon of eight canoes (reservations are needed for all boats; permits are required for those who bring their own). Over the past few years kayaking has grown in popularity rapidly, especially the use of recreational models that differ in size and intent from sea and whitewater designs.

The Pungo I rented for the day (you can rent them by the hour on weekends) is a few inches wider than most sea kayaks, giving it greater stability, and its keel line extends beyond its stern, providing a steadier course than white-water models built for quick movements. It is far easier to navigate in high winds and tides than a canoe. Novices can maneuver on the Patuxent's flat water with little fear.

"In the last year we've seen a tremendous increase in recreational kayaks," said Patuxent River Park Facility Manager Greg Lewis, who bought six one-seat Pungos a year ago and recently added two more. "People who used to traditionally rent canoes are looking to rent kayaks. . . . [They're] easy to learn to use, stable, have lower back support, a place to stow gear, easy to carry."

I had hauled the 50-pound kayak from the Jackson Landing storage area to the boat ramp dock, slipped on the life preserver and stepped--uneasily--onto the bottom of the Pungo. My kayaking experience had been limited to one unhappy excursion during which my guide skimmed across a lake far into the darkness as I splashed through a cross-wind.

Although the park normally does not offer guidance, this time was different. Propelled by the double-bladed paddle, the Pungo slid past arrow arum and tall-stem backdrops of reeds and wild rice. The yellow hull rubbed against tide-muddied leaves of spatterdock. Two ospreys made counterclockwise arcs above a nest built on a pole-and-platform, their flight patterns a presence here long before the run-off from deforestation and tobacco farming helped reduce the river's high-tide depth from 50 feet or more in places to an average of 10 to 20.

The 300-foot ocean-going vessels are gone, as are the watermen's log canoes and the steamboats and the McClure Gun Club's flat-bottomed skiffs, but vestiges of the area's deep history have lasted. I curved around the remnants of a train line's swing bridge that transported vacationers and hunters from the 1890s to the 1930s.

The Maryland-National Capital Park and Planning Commission bought the gun club in the late 1950s and uses the main building as the park's headquarters. It also has bought a Federalist era plantation, Mount Calvert, a red-brick splendor built on a hill close by the site of Charles Town, the county's first seat and the largest shipping port in the state in the early 18th century.

The river is less busy these days, and the M-NCPPC likes it that way. Boating is limited through special-use permits, and jet skis are allowed only at the Clyde Watson boating area 10 miles downriver. The 16 kayaks and canoes suit the park well, producing enough revenue to support the program but not stretching resources.

"I hope we'll stick with right where we are," Patuxent River Park naturalist Greg Kearns said. "I think we've got enough to handle. . . . We have a higher perspective. We're not in it as a profit-making thing."

Lewis, who guides the Kayak Kaper tours (see accompanying box), said the fleet is meant for the curious, not the overly accomplished.

"Once you are in them for about five minutes you're good to go. It's something a beginner or novice can do. You have a flat-water river that doesn't move very fast. They can have an experience that is not threatening."

This kind of kayaking is a long way from the helmeted enthusiasts who dodge mini-icebergs and plunge chutes in rain forests, but a drowsy flat-water trip contains its own joy. You don't have to go far to take in geographic treasures. It is a short paddle away.

PATUXENT RIVER PARK

* HOW TO GET THERE: From the Beltway take Exit 11A (Route 4) to Upper Marlboro. Go south on Route 301. After four miles, take a left at the stoplight onto Route 382. Three miles in, turn left onto Croom Airport Road. The park opens daily at 8 a.m. and closes at 8 p.m.

* PERMITS, FEES, TOURS: The park requires special-use permits or reservations for all activities. For more information call the park office at 301-627-6074.

There are river tours by pontoon boat and Patuxent River Park Facility Manager Greg Lewis leads Kayak Kaper tours. The next tour is Aug. 7. Life jackets and paddles are provided. Cost is $5 per hour for Prince George's and Montgomery county residents, $6 for others. Daily rentals available during the week ($12 bi-county, $15 nonresident). Season runs from April to October.