Divide your family into two teams, pairing older people with younger children. Give them each a list of items to find inside and outside the house. Team members may not split up. The first team back at an arranged meeting place with all items with them inside a bag wins the prize- they drive with Dad to the store and pick out the flavors to make ice cream floats. The losing team makes the floats and serves them (they get to drink them, too.)
a black marble
a bent, rusty nail
a grub or worm
a picture of an owl
something with the word 'joy' on it
a bouquet of wildflowers
a bird feather
a green onion top
a grey hair from someone over 70 yrs of age
You can also play this game with two digital cameras by making a list of photographs each team must take. We plan to play this one next time. You can require different poses the team must do together such as a human pyramid or something silly. They must do something at a certain place. Usually it is something funny.
Another scavenger hunt could be a list of things they must make from a bag of items you give them. For example, they must make a slingshot. The bag of items includes sticks, rubber bands and a green leaf among other things.
What about a nature scavenger hunt? It could be a general list, or a bug list, wildflower list or even a rock (geology) list depending on what you have studied.