Geocaching: Participants use GPS devices to search for hidden caches, boxes containing small prizes or information on nearby attractions, or even jokes. www.geocaching.com
Orienteering: Combines reading topographical maps and compasses with on- and off-trail running. Players "punch in" at control points along a zigzagging course. www.us.orienteering.org
Adventure Racing: Teams use mountain biking, trail running, paddling, and rappelling to speed from checkpoint to checkpoint. Less strenuous races are occasionally organized for children-the starting age is nine-accompanied by an adult. www.usara.com
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