I used to geocache. It was a great way to enjoy the outdoors, explore the area in which I lived, and challenge my intuition. I don't know how well a GPS-enabled phone will work for geocaching, but it is worth a try. Back when I was 'into' the game, the premier site for finding cache coordinates was : www.geocaching.com

If you decide to give it a try, take a small tool kit (flashlight, pair of tweezers, multi-tool knife, pencil & paper, minor first aid stuff) with you. Happy hunting!