Geysir

One of the greatest natural attractions of Iceland and part of the famous "Golden Circle Tour," The Great Geysir, or Stori-Geysir, has been dormant since 1916 when it suddenly ceased to spout. It came to life only once in 1935 and quickly went back to sleep. Since then, its repose has sporadically been disturbed by the dumping of tons of carbolic soap powder into its seething orifice to tickle it to spout. 

It is not exactly known when Geysir was created. It is believed that it came into existence around the end of the 13th century when a series of strong earthquakes, accompanied by a devastating eruption of Mt. Hekla, hit Haukadalur. In this geothermal valley, Geysir is located. What is known is that it regularly spouted every third hour or so up to the beginning of the 19th century and, after that, progressively at much longer intervals until it completely stopped in 1916. Whether its silence is eternal or temporary, no one knows.