Rainbow Pool is a natural hot spring located in the Yellowstone National Park in the United States. It is known for its vibrant colors, which are caused by the presence of different microorganisms and minerals in the water. The pool has a diameter of about 100 feet and can reach temperatures of up to 200 degrees Fahrenheit. Visitors are often drawn to Rainbow Pool for its stunning beauty and unique features. However, swimming is prohibited due to the extreme heat and potential hazards. The surrounding area is also home to various wildlife, making it a popular spot for nature enthusiasts and photographers.