i found this activity recently and got involved its a great way to keep the kids happy whilst green laning or walking, basically you look for things hidden all over the world using your maps and a gps. believe it or not there are loads in Essex. My kids love it and i get to go laning!.
GPS Treasure HuntIf anyone wants to know more just ask,
heres a basic guide:
Geocaching is an entertaining adventure game for gps users. Participating in a cache hunt is a good way to take advantage of the wonderful features and capability of a gps unit. The basic idea is to have individuals and organizations set up caches all over the world and share the locations of these caches on the internet. GPS users can then use the location coordinates to find the caches. Once found, a cache may provide the visitor with a wide variety of rewards. All the visitor is asked to do is if they get something they should try to leave something for the cache.
Paul