Þingvallavatn (Icelandic pronunciation: ​[ˈθiŋkˌvatlaˌvahtn̥]), anglicised as Thingvallavatn, is a rift valley lake in southwestern Iceland. With a surface of 84 km² it is the largest natural lake in Iceland.
The Golden Circle is a 190mile (300 kilometers) route of Iceland's three most popular natural attractions: Thingvellir National Park, the Geysir geothermal area and Gullfoss waterfall.