A Woo Grotto is a term used to describe a specific feature of the first Playboy Mansion located at 1340 N. State Parkway in Chicago. It was a swimming pool with a firemans pole descent and was known for its wild parties and sexual activities. The term "Woo" is believed to have been coined by Hugh Hefner himself, and it was used to describe the sound that women made when they saw the pool.

It is important to note that the term "Grotto" can also refer to other things, such as an installation called the Mermaid Grotto, which was inspired by the Sacred Kiss and offers a more playful context for healing energies. Additionally, the term "Grotto" can refer to a specific location, such as the Grotto della Poesia in Puglia, Italy, which is a popular tourist destination. Finally, the term "Grotto" can also refer to a location in a video game, such as The Cave in Chaotic Bean Simulator.

In summary, a Woo Grotto specifically refers to a feature of the first Playboy Mansion, while the term "Grotto" can refer to a variety of other things depending on the context.