In the event you are not aware of geocaching (I only stumbled upon it this year whilst hunting for something completely different on Google – isn’t that always the way?), it’s effectively a 21st century approach to orienteering (apologies to geocachers who may disagree with my simplified interpretation).
It involves a GPS (rather than compass) and people hunt to find the ‘cache’ (treasure). If you’re that way inclined, check out the official Geocache website for more details. Better still, read the history page to find out how it all started, when one lone computer consultant (it could only be that, or maybe a software engineer) thought he would devise a cunning plan and put to the test the now publicly available GPS selective availability mode.