Green and Tidy
Not all visitors to the countryside are as clean and tidy as they should be. Create a scavenger hunt list based on items other campers have left behind at the site. That way you can teach them about why we shouldn't litter, as well as having them actively help the environment by gathering up dumped objects. The list should feature non-biodegradable object such as: old tent pegs, a plastic bottle, empty food containers, a broken tent pole, coins (extra points for foreign ones), or a plastic raincoat.
Photos
The advent of the digital camera means it's possible to "collect" items by photographing them and showing them to your friends without having to get film developed. This is a great form of treasure hunt for natural objects it might harm the environment to remove such as rare flowers, or for wild animals or landscape shots that would be impossible to "collect" any other way. Such a list should include photos of things like: a wild animal on a tree, a particular type of flower or plant (check nature books for unusual species in the area where the kids are camping), a self portrait of themselves in a particular place, and the view from a specified viewpoint.
Art and Crafts
Challenge kids to collect items they can use later in arts and crafts projects, so they can continue their camping scavenger hunt enjoyment even after their trip has ended. The list should feature items such as: fallen leaves, flowers (of non-rare varieties) which can be dried and pressed, feathers, bark rubbings (made by placing paper against the trunk of a tree and rubbing over it with a crayon), small stones to be painted and turned into paper weights, or shells.
Song and Story hunt
Camp evenings are famous for their ability to provoke funny songs and tall tales. If you are at a busy camp site, set kids a challenge at the start of their trip to collect at least one song, story, poem and joke from other children (and adults you've approved) at the camp and note them down in a book. On the last night, the children can entertain each other with their favorites around the camp fire. Give small prizes for the joke voted the funniest or the spookiest story.