The Columbia Icefield is the largest icefield in Canadian Rockies and one of the largest non-polar ice fields in the world. An absolute must stop MUST STOP along the Icefields Parkway!
This massive icefield feeds several glaciers, including the Athabasca Glacier that you can explore via guided tours or just walk the Toe of the Glacier trail to get a closer look near the glacier's edge. If you plan to do the guided tours - we highly recommend doing a glacier walk rather than a ride with one of the Ice Explorer buses. Not only it is a better experience, but it's also a more sustainable way to explore the glacier.
PS: Do not try to get on the glacier without a guide, it is extremely dangerous as glaciers have many hidden crevasses and the ice can collapse.