I have been to the Grand Canyon, but didn't have the time to sign up to ride the mules to the bottom. I think that it would be terrifying and thrilling at the same time. I have recently learned that I am afraid of heights. (Something I didn't know until a friend drove me to the top of Pike's Peak - straight drops down the side of the mountain a couple thousand feet convinced me). I think I could handle it on a mule! If not, I will walk and lead the mule or just close my eyes and trust the mule!