What's amazing about the water is kids who are impaired on land because of gravity have more independence in water.

They're relating to each other in playing a game -- and for these children, that is one of the greatest concerns.

They're having fun without realizing they're doing work.

In a hamlet or in a forest, in the deep water or on the dry land, wherever venerable persons dwell, that place is delightful.

The capacity of the land should drive decisions on density, which relies on local dispersion of waste water.

You can do this on a land treadmill but water resistance is important. If you have to walk in a pool you have to lean forward.