Which of the following structures contains an artificial body of water for recreational use?

The structure that contains an artificial body of water for recreational use is a swimming pool. Swimming pools are specifically designed and constructed for leisure activities such as swimming, diving, and sometimes water sports. They are typically built with materials such as concrete, fiberglass, or vinyl and can vary in shape and size.

While hot tubs can contain water for recreational use, they are primarily designed for relaxation and hydrotherapy rather than swimming or full-body recreation. Water tanks are usually meant for storage and supply of water rather than for recreational purposes. Fish ponds may provide a recreational aspect, especially in terms of fishing or aesthetic enjoyment, but they are generally not constructed with the primary purpose of recreation in the same way a swimming pool is. Therefore, the swimming pool is the most appropriate answer due to its clear focus on recreational use.