My youngest son needed a 20 mile hike to complete his Boy Scout hiking merit badge. We started at 6:00 am from First Water Trailhead knowing it would be a long, hot day. We took the Dutchman Trail south, by-passing the Bull Pass trail to add milage. We went around the south side of Black Top Mesa, passing Peralta Canyon Trail and Terrapin Trail and went to Cavalry Trail. We continued to head southeast down the Dutchman trail passing White Rock spring where there was quite a bit of water. We met a tortoise as we were hiking up the side trail to Charlebois Spring. This is where we ate lunch - it took a little over 5 hours for us to get here. Charlebois Spring only had a little water, and the water back at White Rock spring was flowing quite a bit more and was clear, so we went back there to replenish our supply. We then headed north up the Cavalry trail through Marsh Valley and on over to Boulder Canyon Trail. I do not advise others to do this in May like we did. It was about 103 degrees and there is little shade. But we stayed hydrated and stopped to rest in what shade we could find. It was a little daunting to look down at Boulder Canyon from the ridge of Cavalry Trail, knowing we had over 5 miles to go! Well, we made it up Boulder Canyon to the Second Water Trail and headed back to First Water Trailhead. My GPS showed 20.01 miles when we got to the truck in the parking lot. This is a challenging hike for 1 day, and very hot in May. But we prepared well. The whole hike took 11.5 hours, but we took several breaks in the middle of the day because of the heat.