V.B.
What is the treasure?
One way to do it is to have goody bags (I know, I know) made up of whatever the prizes you want to use. Then, just put however many goody bags into the big treasure box that they get at the end of the scavenger hunt.
I may be misunderstanding though. I thought on a scavenger hunt you collected random items and then brought them all to the turn in spot to collect a prize. Sounds like you are giving them clues to follow a map to a particular place to find a treasure box.
I did that for my son's 5th birthday. It was a pirate theme. Two "teams" of 4/5 kids each. But I only had ONE treasure box. I set it up so that both teams did all the same activities along the way, just in a different order, so that they finished at the same place while going in opposite directions. They found an item to make their pirate outfit at each "station". It was a ton of fun. Pain in the patoot to figure out the logistics, but it worked.
One group went left around the house. One group went right around the house. Both ended up at the back of our property behind some tall grass where the treasure box was tucked away out of sight, with plastic baubles and beads for everyone (like Mardi Gras stuff). They had to cross a lagoon (a wading pool), walk the plank (jump off the deck over a small bush--our deck was essentially even with the ground, but had raised seating), and a few other things. I had stuck plastic swords (with balloons attached) into the mailbox. So they each got a sword and balloon, after the plank there was a slide, where they got a piece of gold clip on jewelry (single dangly earring), at the lagoon they got an eyepatch (made them out of black felt and elastic string), and after they found the treasure and got the goodies divided up amongst themselves (I gently directed everyone to choose A string of beads and A ring, and X number of plastic gold coins), then a friend of mine (who'd dressed up like a pirate) let them choose a temporary tattoo to apply to the back of their hand or arm or whatever, or take home with them. Each child had their own rolled up "map" that I had made with pictograms of where they were to go on their treasure hunt. Complete with an X marks the spot at the end. Plain tea stained copy paper worked just fine for that, then rolled up and tied with a small piece of string.
Each kid got a bandana when they arrived (red bandanas were one group and black bandanas were the other group--so I'd know who to give which maps).
They had so much fun and were well behaved about choosing beads, etc. They already had a ton of stuff anyway. :)