LETTERBOXING OR GEOCACHING
This is a fun family activity for getting outside. Letterboxing is a mix of treasure hunting, art, navigation and exploring interesting places. The basic idea: someone hides a waterproof box somewhere containing at least a log book and a carved rubber stamp. The hider which are people from all over the world then usually writes directions to the box which are clues or a map, which can be straight forward, cryptic or any degree in between. The clues involve map coordinates or compass bearings from landmarks. (taken from letterboxing.org). There are a bunch of letterboxing websites. Just google search.
Geocaching is very similar but it uses a GPS unit. Adults or younger adults enjoy this particular one.