Lake Toba is a lake formed inside a huge caldera created by the eruption of ancient Supervolcano Toba about 69,000–77,000 years ago. It is located in the province of North Sumatra, Indonesia. The lake is the largest lake in Indonesia and the largest volcanic lake in the world, 100 kilometres in length and 30 kilometres in width, and 505 metres at its deepest point. At the center of the lake lies Samosir Island.
The eruption of the Supervolcano Toba which created the huge caldera is believed to be the largest explosive eruption anywhere on Earth in the last 25 million years with VEI intensity of 8. It has been accepted that the eruption of Toba led to a volcanic winter with a worldwide decline in temperatures between 3 to 5 °C and up to 15 °C in higher latitudes.
Lake Toba and Samosir Island is the homeland of Batak People. According to their traditional tale, Lake Toba was created because a farmer broke his pomise to his wife. This tale is known as the tale of The Origin of Lake Toba.