Roughly midway along the Icefields Parkway, the Columbia Icefield and Sunwapta Pass mark the boundary between Jasper and Banff National Parks, and the dividing line between the Arctic and Atlantic watersheds. South of the pass, the first worthwhile stop is the Weeping Wall, a 350-foot cliff of gray limestone down which a series of waterfalls tumble. Frozen in winter, it’s a prime spot for ice-climbing thrill-seekers.

  Though it may well sound like empty hyperbole, the list of candidates for the most beautiful sight in Banff National Park, and perhaps the entire Canadian Rockies, has to include jewel-like Peyto Lake, an iridescently glowing blue-green glacial lake that reflects the surrounding snow-capped peaks. The often mirror-smooth waters of this small, oblong lake change color from a deep blue to jade green as the proportion of glacial silt in the water increases with the snowmelt from summer to fall. The short trail to the usually crowded Peyto Lake overlook starts from the parking area along the Icefields Parkway at 6,803-foot (2,069-meter) Bow Summit.

  Bow Summit is one of the highest points reachable by road in Canada; south of here, the Icefields Parkway drops down into the Bow Valley, which is dominated by the sparkling waters of Bow Lake and the views across it to Crowfoot Glacier. At the north edge of the lake, historic Simpson’s Num-Ti-Jah Lodge ($C210–255; 403/522-2167) is a giant octagonal log cabin, with well-priced rooms and a rustic restaurant, that marks the start of a popular trail to spectacular Bow Glacier Falls; it’s a fairly level, two-mile (three-km) one-way hike.

  From the lodge, the Icefields Parkway winds along the east shore of Bow Lake, then along the banks of the Bow River, which flows south through Lake Louise, Banff, and on through Calgary, eventually ending up in Hudson Bay.