Inflatable Pool Engineering

My cousin has one of these in her yard and they just seem like brilliant idea to me.

The way these things work is that you check your local building code. If the bureaucrats haven't taken away all your fun you go to the store and buy one. Now you find a sufficiently level space in your back yard and lay it out. Then you blow up the inflatable ring that forms the upper edge of the pool and start filling the pool with water.

The boyancy of the ring means that it floats on the water in the pool and holds up the side curtain walls. This way the sides are simple multi-ply walls of plastic which only have to resist the hydrostatic (and smaller dynamic loads) of the water inside. The hydrostatic static loads cancel each other out because of the round pool's symmetry.

Now your kids can still break the thing with anything sharp. Or they can do it more easily by grabbing the upper ring and just pouring the water out. I don't know whether the kids can actually create enough dynamic forces inside the pool to push the water out, but I kind of doubt it.

These pools even come with a filter unit and chemicals.

My cousin does have her backyard fenced, for those with concerns about that sort of thing.