Woke up in the Colossal Cave campground, in a shady wash surrounded by saguaro cacti. Took off around the hills and down into the low desert Rincon Valley. The saguaros were becoming ever more frequent, and after a few miles, we found a peaceful little flowing stream where we met back up with Erik and met three middle-aged Tucsonan women doing a section of the trail. We chatted and filtered water for a while, and eventually decided to head up further. Huge mistake. It was 10 miles and a couple thousand feet of elevation gain to the first allowed camping in the national park, and we overestimated our energy. At least the sunset and the lights of Tucson below were pretty. Still, we arrived at around 9pm truly exhausted and grumpy.