The water was calm, but suddenly we could hear the turbulance up ahead -- the most exciting moment in white-water canoeing.

Long Jim was standing in the back ofthe canoe, propelling us with a 10-foot pole, while I made fine adjustments in the bow with a paddle.

We had already broken one paddle on the rocks.

"Okay," he said as we rounded the bend, "it looks like the deep water's on the left. See the chute?"

There was a tongue of slick water, presumably the deepest part in the fast water. I pulled the bow that way and we were on line.

We slid between two big rocks, pickedup speed and headed for a foot-tall standing wave.

Long Jim, navigating from his highervantage point, called out the maneuver We banged through the wave and 1 let out a zip.

"Left!" he shrieked.

I dug in hard and pried the boat ontoa new course, knowing that he'd seen an obstacle looming.

"No, no, no," he shouted. "Your OTHER left!"

Too late. In the world of whitewater there is no time for mistakes. For some reason the lobes of my brain had made left right, and we were locked onto a crash course. SLAM, the boat ploughed head-on into a barely submerged boulder. Long Jim came crashing forward on his knees

We leaned downstream and pried off the boulder as the water surged around us. "Funny," said Jim when we were free again, "I knew when I said it you'd get it backwards. I've done it myself a hundred times."

It was the first section of the finalset of rapids in our three-hour spring whitewater journy. We left the P Street Bridge and the chuckling lunchtime audience behind and had soon coursed under K Street and M Street and finally out into the broad, swollen Potomac.

"Hurray," Long Jim shouted. "The Northwest Passage."

Well, not exactly. But we had managed to pioneer the lower stretch of Rock Creek right through the middle ofthe Nation's Capital and found it a charming, instructive and occasionally demanding spring challenge.

It was Long Jim's first try there. I'd made the attempt once before, two years earlier, with another fellow.

That time, we'd gone exactly 300 yards before a pair of Park Policemen beckoned us from shore and told us we couldn't do it, that permits were required.

I had just assumed at that time it was your standard big-city Catch 22: You need a permit and we don't give them out. We packed it in.

But the latest issue of the Canoe Cruisers Association Newsletter provided new hope for a second attempt. It said permits were indeed available, at park headquarters next to the Rock Creek Stables.

It turned out to be a smple matter toget a permit, and once obtained it's good until the end of the year.

It is worth the minimal hassle that goes with the paperwork.

All last week the exciting stretch ofthe Potomac from Great Falls to Little Falls was too high for safe padling. Long Jim and I were anxious to get the boat wet after the long winter. Rock Creek turned the trick.

We scouted the lower two-thirds of the creek and determined that the stretch from Pierce Mill to the main river was navigable, while upstream the level was too low to slip around the boulders that gave the creek its name.

Rock Creek turned out to be challenging -- not all that dangerous, but a good lesson in river-reading. We encountered low-water dams which we had to portage around; "strainers" --fallen trees that can be serious in fast water; sections so rocky and fast that we had to line the canoe through with ropes; hazardous hydraulicsat the foot of the small dams, one of which half-filled the canoe while I sat stupidly pinned in the boat; pools where Jim got to work on his poling technique, and of course, some nice wildlife.

We probably flushed a dozen or more pairs of mallards -- there seemed to be a pair in each pool -- and a wood duck.We found squirrels feeding on the banks, sidled up to a beaver near PStreet and saw at least a million songbirds.

Oh yeah, and a pair of black bears. And a lion. And a cobra. And two monkeys. We stopped at the zoo.

Jim's a veteran whitewater man. Hisassessment of the creek: A fine place to learn and practice in a safe and convenient way all the maneuvers serious whitewater paddlers need to know.

Hopefully others will have their technique ironed out by the time they reach P Street, where the crowds are likely to be. We wanted so badly to go through smooth, looking cool. Instead, we wound up very nearly all wet.

Water level is critical to successfulriver or creek running. The Park Service wants canoeists or kayakers to check the metering station at Sherrill Drive on the creek (just above the Park Police substation on Beach Drive) before setting out.

According to their instructions, the meter there should read between two and five feet.

We spotted two other level gauges along our route, one at the Calvert Street Bridge that read 72 inches and one at P Street that reads 76. Both were attached to bridge pilings.

We considered both those readings to be minimal comfortable levels for canoeing.