Try geocaching—a super outdoorsy activity that involves finding a hidden item (aka hidden treasure, as far as the kids are concerned).
Geocaching: A backyard adventure
Geocaching in N.J.: How to take part in a tech-enabled treasure
NNJC (Northern New Jersey Cachers)
Remains of NJ geocacher Robert Owens Jr. may be found in Louisiana
Introduction to Geocaching, in the Great Swamp
Verona Geocaching Target Hidden In Local Park: Wilbur The Pig
Geo Trail Passport - American Revolution Patriots
GC9JTYW The Central Jersey Island Reverse Wherigo (Wherigo Cache
Geocache causes evacuation in Nova Scotia