Competitive littering. I kid I kid.
Geocaching
Geocaching is a worldwide scavenger hunt that uses a GPS or phone app with GPS. There are over 3 million active caches around the world. Some are as small as a dime, others are big enough to walk into, all of them provide a unique adventure. We invite you to share your stories, photos, and experiences!
It's a community treasure hunting game. A person hides something, then posts GPS coordinates and/or clues to lead you there. Often the hidden item is a sealed container so people can leave log books or unique trinkets. Some of the trinkets have serial numbers you can use to see where they've traveled.
I haven't done it in years, but I remember it being a lot of fun. Hunting for caches led me to a bunch of interesting new places that I would never have explored otherwise.
A fun hobby that was ruined by smartphones.
Am I supposed to take a laptop with me to read the cache description or what?