Taking an Ice Explorer, followed by a a walk on the Athabasca Glacier, was amazing! The Columbia Icefield is the largest mass of ice in the Rocky Mountains. As we'd been to Alaska & seen glaciers calve, I was a little apprehensive. Our driver assured us that we'd be safe though... The Ice Explorers, with massive low-pressure ties, provide all-terrain mobility. It's suggested that you dress in warm layers and wear closed-toe, comfortable shoes with sturdy soles (e.g. sneakers, hiking boots). According to their website: "Guests are permitted to stay on the glacier for 20 minutes." Lastly, according to one online site: The Columbia Icefield is the "largest region of ice and snow south of the Arctic Circle. Melting snow and ice feed rivers that drain into the Atlantic, the Pacific and the Arctic Oceans." An exciting one of a kind adventure!