You'd be forgiven for thinking that a milk carton derby entails individual milk cartons fashioned into miniature boats, but you would be mistaken. This Seafair tradition—which started in 1972 and bills itself as a "quirky celebration of creativity, science, and boatmanship"—invites crafty community members to use a bunch of milk cartons (300 per team) to assemble vessels sturdy enough to hold human bodies. The participants then paddle their creations on Green Lake to win prizes before a group of adoring fans (aka friends and family). The whole affair wraps up in the early afternoon, making for a very productive and sun-soaked Saturday.