"An awesome hike if you're adequately prepared. Here's how to do it in one day safely.
1. Start early. You should set out down the Kaibab no later than 3:30am.
2. Bring a lot of food & water. You burn a LOT of calories & sweat a lot of water. Come prepared.
3. Train properly. Do not do this in one day without being in good shape. Period.
4. Refill water at every place possible. At the bottom and the 3 stations on the way up.
5. The hardest part (in my opinion) is the first 2-3 miles of the ascent along the Colorado river in the sand. Take it slow, drink plenty, rest in shade as you find it.
That's about it. Seeing the sun rise as you descend into the canyon is something I'll never forget and everyone should experience. Just be careful to not waste too much time hiking down to the river or else it'll be pretty scorching on the way up. We took our time and it was over 100 when we started our ascent. Be careful, but have fun. And be sure to take a picture with the sign encouraging you not to hike rim to river to rim in one day!" Visited on Jul 29, 2009