Slackline walker Dean Potter is featured in this video walking across a precipice without a safety line in Lost Arrow, Yosemite. He is approximately 1,200 feet above Yosemite Valley, bare footed on a nylon rope 70 feet across. The difference between a tight rope and a slack line is that there is very little movement on a tight rope where as a slack line undulates.

Using just his arms to balance, he walks from one cliff wall to another with his bare feet. Although you’ve got to give him credit for courage, you can’t help wondering what insanity would make him want to do it.