This is a popular kayaking spot in Washington. I was photographing with a friend and from what I remember there was not enough water for him to take the plunge. They say that it is about 30 meters tall (100 Feet). With more water the kayakers go off the waterfall and as they are falling, partway down they enter the tube (enveloped by the water and disappearing from sight). Rather than impacting flat water from 30 meters, they are going with the heavy flow of the water, safe and sound.