Geothermal power station at Svartsengi, Iceland. In the foreground, bathers & people suffering from psoriasis enjoy the benefits of the 'Blue Lagoon'. Waste geothermal water from the power station fills the lagoon; the water is at a temperature of about 70 degrees C, & has a similar salt content to sea water. About 1000 tons of the water flow into the lagoon every hour, gradually seeping into the surrounding volcanic lava. Particles of silica form in the water & geothermal algae grow there, contributing to the brackish, clayey mud which apparently helps to cure people suffering from psoriasis, a type of skin disease.