The excellent, if challenging, Crypt Lake hike is regularly touted as one of the best in Canada. The 17km out-and-back hike involves a boat trip ($20) across Upper Waterton Lake to a trailhead on the east side of the lake.
A (perfectly safe) climb up a ladder, a crawl through a rock tunnel and a section along a rocky ledge with cable for support all form part of the 675m ascent.
The rewards are the crashing waterfalls and the great glacial amphitheatre containing Crypt Lake (1955m); rock walls tower 600m on three sides, casting a chill shadow that preserves ice on the lake throughout the summer.
Allow time to catch a return boat!