The walk along Johnston Canyon is pretty easy; part of it is boardwalk, and there are several well-placed benches along the way. So it was ironic that here, of all places, was where I jammed my knee when I took a misstep. It was sore for the rest of the vacation but fortunately didn't inhibit my activities too much.
To the right of the falls, there's a low tunnel that leads up to a view point that is close enough to the rushing water that you get sprayed and the rocks underfoot get quite slippery.