Words from Ben Stookesberry's scouting before the trip: "Hells Canyon of the Snake (popularly known as the deepest canyon in North America) is 8000 feet deep on one side and 5643 feet deep from the other at just over 10 miles wide.  Mexico's Rio Piaxtla squeezes through a corridor just 6 miles wide that is 7852 feet deep from river right and 6000 feet deep from river left. Certainly the depth of a canyon should be taken from it's lesser wall or at least the average of the two."