Apparently, shipping containers make good swimming pools
Making a pool can be as easy as digging a hole and filling it up with water but if you want to make something a little more permanent Vancouver-based Modpools say that shipping containers make the perfect for swimming pool.
While they're still not 'light' by any stretch of the imagination, they're 'semi-portable', unlike a tradition swimming pool that'll probably be stuck in the ground for an eternity; you can even take it with you if you move house.
The company also adds a window to the side of the container. Making a spa pool isn't too hard either by the looks of things, all it takes is a divider: