Samosir is a large volcanic island in Lake Toba. Lake Toba is located in the north of the island of Sumatra in Indonesia. It is a popular tourist destination due to the fantastic vistas it offers. The tourist resorts are concentrated in the Tuktuk area; some of the best known hotels are the Samosir cottages and Carolina's. The island was a centre of the Batak culture and its remaining artifacts are part of the island's tourist appeal.

Samosir was turned into an island artificially; it was originally a peninsula that was transformed into an island when a canal was cut through the isthmus connecting it to the caldera wall that surrounds Lake Toba.