What you're actually looking at
The Columbia Icefield is the largest icefield in the Canadian Rockies, and Athabasca Glacier — the tongue of ice visible from the highway — is just one of eight major glaciers it feeds; the meltwater eventually reaches three different oceans, the Pacific, the Atlantic via Hudson Bay, and the Arctic. It's also visibly shrinking: the glacier has retreated more than a kilometre since the 1890s, and the access road to it is lined with small dated signs marking where the toe of the ice used to reach in different years. Walking from today's parking area to today's ice edge means walking past a century of that retreat, one marker at a time.
How close you're actually allowed to get
On your own, for free, you can walk to a roped-off viewing area near the toe of the glacier — and that rope is the real limit, not a formality. Athabasca Glacier hides deep crevasses under snow bridges that can look like solid ground, and unroped visitors have fallen 25–30 metres into them, some fatally; going further legitimately requires a guide. That's what the paid options actually are: the combined Ice Explorer (a specialized bus driven out onto the glacier) and Skywalk (a glass-floored platform over the Sunwapta Valley) ticket runs roughly C$116–126 for an adult, with about 20% off on departures after 3:30pm, seasonal from roughly May through October and needing to be booked ahead rather than bought at the door. Either way, dress for it properly — this is the corridor's most exposed stop, and wind coming off the ice makes it noticeably colder than the temperature back at Saskatchewan River Crossing would suggest, even in mid-summer.
Sleeping at 2,050 metres
Glacier View Lodge, inside the Discovery Centre building itself, is the only accommodation at the icefield — a short walk from the glacier, considerably pricier than a standard highway motel, but the only way to wake up here instead of driving back. Its own booking package pairs an evening and a following-morning tour, so a ticket bought through the lodge covers both without a separate reservation. See Plan Your Day for how this compares to overnighting at Saskatchewan River Crossing instead.