We wanted to finish the unit on navigation with something memorable, and decided on a treasure hunt on Treasure Island.
Caterina found wooden wine boxes at an arts supply store. We worked through the night converting them into treasure chests and filled them with beads, bones, art supplies, glass eyes, and of course coins.
We decided to associate each child with a historical pirate, and chose "Calico Jack" Rackham and his crew, which included the female pirates Mary Read and Anne Bonny.
I drew treasure maps, aged them with coffee overnight, and drove to Treasure Island at dawn to bury the chests on a deserted beach near the Marina.
The night before we had told the children a story about the crew of Rackham's ship The Kingston. In the morning each child found a map waiting at the breakfast table, presumably drawn by the pirates themselves.
Dressed appropriately as sailors we chartered a boat from Pier 1½ to Treasure Island Marina. Luckily it was a beautiful day!
With the help of their maps and a metal detector (and after a decent bit of shoveling) the children all found their Jolly Roger-inscribed chests.
The rest of the morning sailed by picnicking and playing in the shallow water. When it was time to go, we all wanted to stay.