The Athabasca Glacier, located in the Canadian Rockies, is one of the most visited glaciers in North America. It's about 6 km long, covers an area of 6 km2, and is between 90-300 meters thick. Unfortunately, it's receding at a rate of about 5 meters per year, losing over half its volume in the past 125 years. You can pull off here and look around or book a tour to get onto the glaicer.