Paint a bunch of rocks gold, put them into drawstring bags and call it treasure (I always made the bags different for this one). Have the kids split up (match skill sets if you need to) and challenge them into making maps to find their hidden treasure. The maps can be as simple or complicated as you decide to make the guidelines. Kids love to make color-coded ones. After they make their map, the maps are traded and then the challenge is to find the hidden treasures. (Old costume jewelry is really fun for this as well).
I used to do this where I hid the treasure and made maps for the kids to follow when they were younger. As they aged, I used a compass and orienteering to increase the challenge.
I still have requests from people for this activity.