A Canadian company has converted standard, metal shipping containers into pools and jacuzzis that can be installed above or below ground. A portion of one wall is cut away to make room for a viewing window. The pool also comes equipped with an interior partition made of sturdy, heat-resistant plastic that is used to separate it from a jacuzzi. https://www.dezeen.com/2017/05/03/modpools-repurposes-used-shipping-containers-swimming-pools-hot-tubs/