The Columbia Icefields is pretty much halfway through the drive to Jasper.

You can walk around from the parking lot along the parkway to The Toe of the Athabasca Glacier for a an upclose look. This is about 1km. Alternatively, you can take guided tours to explore the glacier and actually go on it. There are a lot of companies doing this tour, but we have heard great things from the Ice Explorer at Viator. You go on it it one of the big ice jeeps that is shown in the picture!