A gentle leg-stretcher that's well worth the couple of hours or so it'll take to walk to the falls and back. The falls are huge as the 150-m-wide Kicking Horse River drops 30 metres over an escarpment.
Hiking the trail is very easy and there is a loop which takes you down to the river level below the falls for a closer look, and to bathe in the cool spray. The trail looks like it can get really muddy and/or flooded in wet conditions, so despite it being easy, boots are recommended. Do this hike on the day you arrive or leave the Yoho area.
Note that access is only signposted heading east along Highway 1; if you're heading west, you need to 1) recognize the sign in your rear-view mirror and 2) find a safe place to turn round a couple of kilometres further up the road. Not easy if the road's busy, but should be possible. Do not try and make the left turn from the westbound lane!