In King's Canyon National Park. This canyon, at its deepest point, is 3,000 feet deeper than the Grand Canyon. My wife was very uncomfortable (can you spell "understatement") during our drive from the top to the bottom (and back up). This image is somewhere near the mid-point.
The VW Beetle lends a sense of scale.
Two other views - http://www.pbase.com/ed_k/image/87309519 - and - http://www.pbase.com/ed_k/image/87309520