The Blue Lagoon is a geothermal spa in a lava field in Grindavík in southwestern Iceland. Originating at 2,000 meters below the surface where freshwater and seawater combine at extreme temperatures, the geothermal water is then "harnessed via drilling holes at a nearby geothermal power plant, Svartsengi, to create electricity and hot water for nearby communities." The geothermal water is composed of three active ingredients—silica, algae, and minerals—and the blue color comes from the way the silica reflects sunlight (algae in the summer may also produce a hint of green), but if the water is poured into a transparent cup, it will have a milky white color! The water is supposed to be great for your skin, but I wouldn't drink it.