PETERBOROUGH - High above the riverbank trees, an osprey stick nest crowns a hydro pole. My eyes swing downstream and there the osprey, its underside stark white against the blue of the summer sky, soars and swerves on shifting currents of air, 200 metres from our boat.

We pass two loons who cry to each other from 300 metres apart. From the sun deck, six of us watch in silence, wary of breaking the spell.

We're on the Kawartha Voyageur, gliding along the Trent-Severn waterway from Peterborough to Big Chute.

"Most Ontarians don't realize that water covers one-fifth of this province," says Marc Ackert, the captain, as we cruise past forested islands in the Kawartha Lakes.

For natural beauty, it's hard to choose between the Peterborough - Big Chute and the Ottawa-Kingston cruises. The Kawartha Lakes of the former and the Rideau Lakes of the latter have to rank among the scenic splendours of the world.

Summer homes, resorts and farmland co-exist with forest, more so through the Kawarthas than along, the Rideau Lakes, but from the sun deck of the ship, the eyes embrace a world of beauty around every lake and along every channel: sparkling blues and silvers bordering green velvet in summer and a kaleidoscope of colours in fall.

If you like action on your holidays, skip these cruises. On the Kawartha Voyageur, there's nothing to do but lie back and enjoy as the world drifts by, slowly, smoothly. Bird watchers are in their element.

For the Big Chute cruise, we boarded the Kawartha Voyageur at Peterborough's Little Lake on a summer Thursday evening. We took off at breakfast Friday, through the Otonabee River to the highest hydraulic lift lock in the world. Sailing into a bath-tub-like basin at the foot of a castle-like structure, we were lifted 20 metres as the twin bath tub beside us lowered its load of boats.

We stopped at Bobcaygeon, whose clipped lawns and sparkling flower beds snuggle along the narrow, curving waterway between Pigeon and Sturgeon Lakes and whose stores lured our souvenir hunting passengers.

Fenelon Falls, on a short, rock-walled stretch of the river between Sturgeon and Cameron Lakes, with its lock in the centre of town and the picturesque falls beckoning the photographers on board, sold its share of souvenirs.

The most interesting stop on this trip had to be Orillia, population 24,000. Here, on the shore of Lake Couchiching, where we tied up overnight and remained until noon, passengers walked through the lakeside park and marvelled at the town's magnificent monument to Samuel de Champlain, considered among the finest examples of bronze statuary in Canada.

Some of the most spectacular scenery was that along the Severn River between Sparrow Lake and Big Chute. Here was north country beauty, the rugged, eternal rock of ages channelling the river past granite islands and promontories, and walling quiet pools where white and yellow water lillies rose gently on our wake. Our cruise ended at Big Chute.

From Big Chute, after a couple of hours to see the railway in operation, Ontario Waterway Cruises bused us back to Peterborough and our car. The boat trip had taken five days. The return bus took 2-1/2 hours.

The Trent-Severn waterway has been in service as long as man has trod these parts. Huron Indians used it on their forays south into Iroquois territory. Champlain accompanied them on one such foray in 1615. It became a waterway for the lumber industry, then a commercial navigation route before railways took business away. The first lock was begun at Bobcaygeon in 1833 but the 386-kilometre (240-mile) system from Lake Ontario to Georgian Bay was developed in stages and took 85 years to complete.

The Rideau system, on the other hand, was built after the War of 1812 to provide a safer route than the St. Lawrence should war again break out with the United States; hence, the blockhouses still to be seen along its route. It was completed in six years, in 1832. It also briefly became a commercial route.

Now, both systems are leisureways, operated as part of Canada's National Parks.