This swimming pool has solved the problem of space as it disappears completely, becoming a solid floor when desired. The swimming pool with water and everything is still there, it is just that there is a floor on top of it. In addition to providing space as for a badminton court, it also reduces heating costs by keeping the water isolated when you're not in it.
The only problem is that it is probably expensive. The website (hydrofloors.be) does not say how much a Hydro Floor Disappearing Swimming Pool costs.