Rock running is my favorite outdoor sport. I can't actually take credit for starting it, but my ex girlfriend had gotten me into it. It started over 20 years ago, in the Black Forrest of Germany. We were doing a nature walk when she saw a hill with plenty of large scale rocks embedded into it. She'd challenged me to a race to the top of that hill, using nothing more than our feet. Any hand contact, with the rocks, results in starting over. It was fun and exhausting. The trick was about maintaining balance while jumping from one rock to another. She was very good at it; running and jumping from rock to rock, like a grasshopper, while I was struggling to simply make a successful jump. As you'd guessed, she won hands down; in retrospect, I think she'd set me up for failure. Every time I go nature walking, I come across at least one hill with many rocks on it. Without hesitation I ask myself, "Can I scale that hill without using my hands". From there, I'm on my way up the hill. The reason why I don't want to take credit for this activity was because of a dance video I'd seen. [ame=http://www.youtube.com/watch?v=oTLJjoW867g]YouTube - ‪Delerium - Silence (featuring Sarah McLachlan) - Tiesto Remix edit‬‎[/ame] Clearly I, nor my ex girlfriend, had came up with the idea first. All that I can tell you is this. It's fun. try it some time.