Rising to the west of Sunwapta Pass, the dividing line between Banff and Jasper National Parks, the massive Columbia Icefield is what the Icefields Parkway is all about: the largest ice field and most accessible glacier in the Canadian Rockies, seemingly endless square miles of solid ice sitting high atop the Continental Divide. Although it has been visibly shrinking for nearly a century, the ice field is still immense, and you can get an up-close look by joining the popular Glacier Adventure tours (888/269-0524, C$85) operated by the Brewster company, which leave every 15 to 30 minutes, depending on weather, to travel out onto Athabasca Glacier.
Overlooking the ice field from across the Icefields Parkway is the modern Columbia Icefield Discovery Centre (daily mid-Apr.-Oct., free), a mini museum of glacial lore operated by Parks Canada. If you want to experience the ice field up close, buy a ticket and take one of the Ice Explorer tours; don’t simply walk across the highway and clamber up, since it only takes one false step to fall to your death into one of the deep but invisible crevasses that crisscross the glacier.
The Columbia Icefield Discovery Centre is also the starting point for visits to the Canadian Rockies’ newest attraction, the Glacier Skywalk (C$29), a transparent-floor observation deck that juts out over Sunwapta Canyon from alongside the Icefields Parkway. Frequent free shuttle buses make the quick trip from the Icefield Centre, but if you want to walk out onto the vertigo-inducing platform, which hovers 918 feet above the valley floor, you need to pay a pretty steep fee.