I chose North to South Rim due to the North being much higher elevation. Going down is taxing however less feet to climb is more inviting. Trails rim to rim are well maintained. Water access is abundant so long as you do not lose water from your hiking unit. Temperature at the bottom is generally at or close to reported degrees in Phoenix, AZ. Early morning departure found spitting ice crystals at the north rim. It was 120 degrees at Phantom Ranch. To escape the burdensome temperature a 2 a.m. departure was executed from Phantom Ranch. By doing so Jacobs ladder on Bright Angle Trail was climbed in coolness. On average I move only one mile per hour including picture taking and breaks. I have observed younger folks jogging with only a water bottle. A duo of young ladies were on their way from the north rim within a few hours they would complete a round trip from south to north and back. Be young, travel light, enjoy the Grand Canyon night.