Children's outdoor play is different from time spent indoors. The sensory experiences are different, and different standards of play apply. Activities which may be frowned on indoors can be safely tolerated outdoors. Children have greater freedom not only to run and shout, but also to interact with and manipulate the environment. Children are free to do 'messy' activities outdoors that won't be tolerated indoors.
Natural outdoor environments have three qualities that are unique and appealing to children as play environments - their unending diversity; the fact that they are not created by adults; and their feeling of timelessness - the landscapes, trees, rivers described in fairy tales and myths still exist today.