We've heard of marathons and triathlons, but imagine running the entireGrand Canyon from rim to rim. That's 42 miles, with ascents as high as 11,000 feet. (And it only took the record holder a little over 7 hours to run.) We get a Fronteras report from KNAU in Arizona about ultra running, and what it takes to run one of the world's seven wonders.
Fronteras: The Grand Canyon
