Container Pool

Not really essential? but how nice is this, a swimming pool lined in a shipping container and another as an enclosure.
I think I would fill a 40' container half way up with sand and gravel then have a long shallow lap pool but have it at an sloping angle so it naturally overflows in to a natural pond where it can be filtered using reeds, charcoal sand and stone before being pumped by solar back to the other end and and keep a full natural cycle instead of chorines and chemicals, hey maybe even make it into a aquaponics system get some fish in there to swim with LOL.

Another example