From Crown Beach, you can hop the freeway to another entertaining waterfront. Imagine a playground that is constantly reinvented and reconstructed by the children themselves. Then take all that old lumber you've been storing because you can't quite bring yourself to haul it to the transfer station (except the really sharp splintery stuff) and pay a visit to the Adventure Playground to see what it's really like. Inspired by the observations of a German playground designer just after WWII who saw that children preferred playing building games in the dirt and rubble of bombed out buildings to playing on tidy asphalt of a nearby playground, this is an unique ongoing experiment that started in 1978 and continues to look promising. Ships, towers, houses, and castles built from donated materials rise and fall with the regularity of the seasons under the influence of tools wielded by wee ones and their helpful parents. Unaccompanied children must be at least seven years old, and will be supervised for up to three hours for $5. Children accompanied by an adult do not have to pay.