Lake Toba is the largest lake in Indonesia and the largest volcanic lake in the world. The lake is 100 kilometres long and 30 kilometres wide, and 505 metres (1,666 ft) at its deepest point.
Lake Toba located in the middle of the northern part of the Indonesian island of Sumatra with a surface elevation of about 900 metres (2,953 ft). Lake Toba is the site of a supervolcanic eruption that occurred 69,000-77,000 years ago, and which was the most recent super volcano eruption.
Lake Toba has an island in the middle, named Pulau Samosir, was joined to the caldera wall by a narrow isthmus, which was cut through to enable boats to pass; a road bridge crosses the cutting. Samosir island is the cultural centre of Batak tribe who are mostly Christians in the modern days.
There are three megalithic sites on Samosir island bear witness to the glory - and horror - of Batak history. The three consist of 300 year old stone seats and benches arrayed in a circle. The first set of ruins was used as a conference area for Batak kings. At the second site, the king would sit in judgment of a criminal or enemy prisoner. If the accused were found guilty, the assembly would move to the third set, which features the ghastly addition of a central stone execution block.
The Air Panas (hot springs) is on the other side of the island to Tuk-Tuk. The hot springs are not on Samosir Island but it's no need to take a ferry off the island to see them. On the opposite side of the island from where Tuk-Tuk is there is a town called Pangururan. There is a small isthmus that connects the island to the mainland. On the other side of this isthmus the hot springs is located. It takes about 1 hour to ride the local bus to Pangururan from Tuk Tuk or shorter by a motorbike that can hire from the rentals around the island.
Kick back and relax after the frenetic atmosphere of Indonesia. Swim in the volcanically warmed waters of the lake or arrange an overnight 'party' boat out on the lake. A beautiful place to do nothing at all.