First a lesson on glaciers. A glacier is a constantly moving river of ice. The Athabasca Glacier moves a few centimetres every day and for the past 125 yrs, it has been retreating, losing 1.5kms in that time. The glacier forms when accumulated snow turns into ice and the ice flows outward between gaps in the surrounding mountains.
The Athabasca is the largest glacier in the Canadian Rockies and the most accessible. You can take a Snocoach tour onto the glacier everyday in summer. There is also an informative Visitor Centre located here.
These are monster coaches with monster wheels designed to carry tourists through steep, slippery ice onto the glacier. Although they are expensive and touristy (I paid $29.95, Canadian dollor, as of June 2003), it's worth it because they take you to places you can't get to otherwise. You can purchase the ticket in the Icefield Centre on the opposite side of highway.
Still, if you choose to hike up the glacier, the Park offers guided walks as well (very limited schedule, I think once a day). But you have to stay on the trail and within the safety barriers. You can't really go far this way, and people have fallen into crevasses and died.
The Columbia Icefield is home to the largest glaciers south of the Artic circle, and it does not disappoint. The aptly named Icefield Parkway pass near the Athabasca Glacier. Unguided hikes on the glacier is not allowed. Tourists (primarily those from warmer climes :) can hop on a "Snocoach" for a tour of the glacier.
Take your time - relax the mountains & rivers aren't going anywhere.
The little critters appear - then disappear = grab the opportunity when you can
(my picture) Tour the Ice Fields. The year this picture was taken it was so mild that the ice had nearly all melted in this area. There was still a lot up in the canyon.