Geocaching is SO much fun! It's like treasure hunting with your GPS. We love finding interesting places - both at home and when we travel - that we would never have found otherwise. The website is www (dot) geocaching (dot) com
We especially love coming across trackables, which are items or coins with a special code that you log in to track that item's travels. Geocachers pick up and drop off trackables, post pictures of their adventures, etc etc. Many trackables have "missions" that they hope to accomplish, such as "reach the Bahamas" or "go to State parks". We always bring trackables with us when we travel cross-country (we travel a lot between VA - FL - WA) to help the items rack up "mileage".