Blue Lagoon is a geothermal spa located in Grindavík, Iceland. It is renowned for its milky blue waters, which are heated by the nearby geothermal power plant. The lagoon is rich in minerals such as silica and sulfur, which are said to have healing properties. Visitors can enjoy a relaxing soak in the warm waters, as well as a range of spa treatments. The lagoon is also a popular spot for swimming, snorkeling, and other water activities.