Find out about letterboxing and goecaching! It is a way to mix treasure hunt and hiking, and can be efficient for children or people who don't see the point of going for a walk, a hike or a treck, who don't enjoy just the pleasure of walking, breathing fresh air and being outside, but need a goal, a reward for their efforts......
In class, this text is a good material for written comprehension for students who have studied English for at least 4 years, because it deals with something nobody knows about and that the class will discover together. It will develop their skills for global comprehension, like scanning a text for information and inferring the global meaning from a few well selected clues.
And then the students can debate about the interest of this sport/hobby....and if they find it is a good idea, why not get into the project and do it in France? This could make American people want to come and visit France!
Here are some links to other site dealing with the subject, that you can use to build a webquest or a treasure hunt:
(from the Smithonian, a short article explaining how it started)
http://freespace.virgin.net/g.sargent/letter.htm (the origninal from Dartmoor, UK)
http://walking.about.com/library/weekly/aa073001a.htm ( with interviews from walkers to read)
http://www.geocaching.com/ (about orientation)
http://members.aol.com/Letterboxr/stamps.html (about how to carve stamps)
http://dmoz.org/Recreation/Outdoors/Letterboxing/ (a very long page of links)