Basically, you want your kid outside in nature as much as possible. Natural playgrounds give kids more chances to develop their gross-motor skills than traditional swing-and-slide playgrounds. Contact with nature has been associated with number of health benefits for children, such as improved cognitive function, increased creativity, improved interaction with adults, reduced attention deficit hyperactivity disorder symptoms and reduced rates of aggression.
You can also make it at home. There’s the drive, then a long hike down a steep hillside of slippery yellowish clay. A small creek, stumps, sticks, trees, dig-able sandy soil, rocks to climb, and a standstone wall full of tube worm fossils.