Embark on a high tech scavenger hunt, using your phone to sniff out any of a million-plus geocaches hidden by players in more than 100 countries. The app grabs GPS data to list nearby spots and provides coordinates to help you pinpoint them. Don't expect treasure — just a logbook and maybe some trinket — but the hunt is plenty rewarding.
WIRED Photos to help if you're stuck. Online logs and field notes let others know about your find.