Geocaching
In 2012, the State Parks initiated the "Geocache Challenge" - much like the Ultimate Outsiders, you were supposed to find the official regional cache in each of the 47 state parks. Using clues from those, you needed to find four mystery caches and then the Finale (52 total). While the "Challenge" isn't 100% supported anymore, most parks still have the official one active and those that don't, have other Geocaches to find. Just don't count on finding the mystery caches.