White-water excitement, still-water serenity. Canoeing, a sport of many moods, is fast rising in popularity

Three canoes, one a gleaming red and two bright green, travel in line about 50 feet apart. Paddles flashing in the late morning sun, they move steadily toward ``The Barryville,'' a mile-long set of modest rapids on the beautiful upper Delaware River. The lead canoe swings into the turbulent water, edging dexterously past a couple of ominous boulders. Twisting and turning, the craft shoots through the noisy water. The others appear less confident. Paddles flail wildly as the canoeists battle to keep their crafts from ``broaching,'' a movement certain to result in an unwanted dip in the foaming water. Within 10 minutes all three canoes have maneuvered through to quiet water and are heading downriver to a picnic spot.

``Wow,'' sighs a gray-haired canoeist. ``What a ride.'' He whistles in delighted relief. A slender, blond man in the bow of another canoe turns toward his stern paddler. ``Hey, Jeannie,'' he grins, ``you really can handle that paddle.'' She smiles appreciatively, then leans back to absorb the sunshine.

This tiny armada is representative of the new breed of outdoor enthusiasts who flock by the thousands throughout the summer to paddle on America's rivers and lakes.

This particular group includes a broad range of ages, backgrounds, and abilities, and it is evenly divided between men and women. They are on a two-day weekend trip, paddling 35 miles from Narrowsburg to Port Jervis, N.Y., on the sparkling Delaware River as it winds through isolated, wooded valleys, beneath high cliffs, and past small river towns born before the Revolution.

Canoeing has enjoyed an explosive growth in the last dozen years. One reason, certainly, is that it offers such a wide range of choices. It can be a sport for serious play in foaming white water, a mode of adventurous transportation through the Canadian wilderness, or useful for a gentle day trip through a quiet swamp.

For those eager to take paddle in hand, perhaps the best way to get involved is with a canoe or outing club, or with one of the many small outfitters that offer personally guided trips. However, it is also simple to rent a canoe from the more than 400 liveries around the nation and try it on your own. A list of some 200 liveries, plus canoeing tips, is available free from the National Association of Canoe Livery Operators, 8600 West Bryn Mawr Avenue, Suite 720, South Chicago, Ill. 60631. Telephone : (312) 693-0990.

Curiously, few liveries offer paddling instruction. Yet training in proper paddling techniques is a tremendous assist in teaching a canoe to behave in the manner you want it to. Training also includes learning how to ``read'' the water, a matter of importance for successfully negotiating any type of white water, from a pleasant rock garden to a roaring set of Class III rapids.

However, if your friendly neighborhood livery does not provide instruction, canoe and outing clubs usually do. And many Red Cross chapters also teach basic canoeing skills.

Don't get misty-eyed visualizing yourself gliding silently along, mile after mile, without sweat or effort. Paddling takes both. If drifting and sunbathing are your thing, you'll be better off rafting in one of those floatable tubs that take the challenge out of water.

Canoeing can be enjoyed for a modest cost. In the Northeast, for example, rentals range from $9 to $12 a day, with discounts for weekend or week-long use. Be aware that liveries expect to be paid in cash and will hold a deposit. Reservations are a must on the more popular canoe rivers throughout the nation in summer. Generally, liveries will haul you and your canoe to a put-in point and pick you up at your take-out point -- often for a fee. Many have campsites at their main base or can advise abou t camping facilities.

Canoes come equipped with paddles and PFDs, or Personal Flotation Devices, the technical term for a life jacket. Make certain equipment is in good shape before accepting it. Ask for at least one extra paddle per party. It will prove invaluable if a paddle is lost or broken.

Rental canoes are generally made of ``plastic,'' or ABS (acrylonitrite-butadiene-styrene), or aluminum. ABS canoes are virtually indestructible and much quieter in the water than aluminum. And they glide easily off rocks that aluminum canoes get hung up on.

Dress for canoeing is basic. Wear old clothes or, for a hot day, shorts or a bathing suit, and an old pair of tie-on tennis shoes. Bring a towel, a bottle of sunscreen lotion, sun glasses, and -- highly recommended -- a wide-brimmed hat. Then, top everything off with your PFD. (You can always separate the veteran paddlers from the novices. The veterans are the ones wearing their PFDs.)

Carry extra gear in something waterproof, such as the five- and 10-gallon plastic buckets with tightfitting lids favored for home repair materials. Add a plastic bottle with the bottom cut off for bailing, and toss in a sponge for tidying up, plus 15 feet of sturdy cord.

You can use the latter to tie your craft to a nearby rock or tree while you take a break and stretch out on a grassy bank to enjoy this versatile native American sport -- canoeing.