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Some basic settings and tweaks of your smartphone can turn it into a very reliable and useful GPS on the trail. Instead of carrying a dedicated GPS unit, I use my phone and the Gaia GPS app with custom maps and rasters. I bring along extra batteries purchased from Amazon. The Samsung S5 is a great hiking GPS coupled with the Gaia GPS app as long as you tweak the settings to conserve battery power. Garmin GPS's are crazy expensive and if you don't need the features that they have and simply need a hiking/walking GPS, try using your smartphone!
Batteries I purchased for S5: https://amzn.to/2Fq8jCA