The United Nations have declared 2017 as the Year of Sustainable Tourism for development. Sustainable tourism is defined as the development or activities in tourism that respect the environment and ensure long-term protection of natural and cultural resources. The Blue Lagoon in the Reykjanes peninsula formed in 1976, fed by the water output of the nearby geothermal power station in Svartsengi in Grindavík. It soon became clear that bathing in the lagoon had positive effects on the psorisasis skin disease. The reservoir has over time become one of the most popular tourist destinations in Iceland. Its ecosystem is one of its kind in the world. The lagoon holds nine million liters of geothermal seawater which is renewed every 40 hours. Its temperatue is of 37-39°C.