Find a Geocache
If your children love a good Easter egg hunt, then they'll love the high-tech fun of a global game of hide-and-seek known as geocaching. To begin, register at a geocaching website and discover the exact latitude and longitude of a hidden cache of "treasure" placed on public property. Geocaches are hidden across the globe, so it's likely there will be one near your camping or hiking destination. Then, using a handheld GPS (global positioning system) to navigate, as well as a trail map, search for the cache, which is usually a trinket or two stored in a container with a logbook for recording who found it. Replace the treasure with one of your own devising for the next person to find.
It's exciting for children to find the actual cache, but it's even more exciting to look for it. If the idea's a keeper, you could always look up additional geocache locations on your camping trip or make the searches part of a daylong outing that includes a hike and a picnic.