I had a trip to 5040 on Sept 2, 2017. One of the purpose of this trip is to test smart phone as GPS for backcountry trips. I relied on Gaia App on an iPhone 7plus for two whole days. About 5040 Cobalt lake was unbelievable. Comparing to the summit, I enjoyed the lake more. The temperature was probably between 20 to 30+ for the three days. We didn't use our tent fly. Air was dry. Washed a shirt. It's dry over night. About Gaia I have only seen my friends using GPS handhold devices. I have waited for better options for years. I have always hoped that my smart phone can do the same. I finally decided to test this idea. I have relied on my iPhone 7plus as GPS on this trip, I think Gaia on an iPhone meets my need of a GPS. My two concerns were, battery life, and robustness. To save the battery, I turn the airplane mode on, also the phone has power saving mode. Which turned off some background process according to the help message below that setting. During this trip, I...