In public spaces all over the world, there are over 3 million cleverly hidden containers just waiting to be found. They are part of the world’s largest treasure hunt, called geocaching. To join in the fun, you can start by looking in your own neighborhood.

The containers vary in size. Each contains a log to sign to prove you found it, so bring a pen. You can also log your find in the app to keep a record of all the caches you’ve found.

Some geocache locations have larger containers in which you might find small items to trade. The idea is, if you take something from a cache, then leave something, the website says. There are also items with a tracking code.

These are meant for you to move to another geocache, and they can be tracked with the app as they travel the world. But it’s not about the items you find; it’s about the experience and adventure, Dave Rinard, who has geocached with his three daughters, told The Epoch Times. “It’s all about the hunting, and finding, and hiking, and being outdoors,” he said.

Mr. Rinard said he has geocached a lot in his own neighborhood in Walnut Creek, California, close to Mount Diablo, while hiking the ridge lines. “[Geocaching is] a reason to get out either in the early morning or late afternoon with the kids, and you’d see wildlife, even rattlesnakes,” he said.

“So we’d always bring a stick with us or a hiking pole, and so before you go flipping over rocks or sticking your hand in a hole, you want to poke around a .