The Toba eruption was a supervolcano eruption that occurred about 74,000 years ago during the Late Pleistocene at the site of present-day Lake Toba in Sumatra, Indonesia. It is one of the largest known explosive eruptions in the Earth's history. The Toba catastrophe theory is that this event caused a severe global volcanic winter of six to ten years and contributed to a 1,000-year-long cooling episode, resulting in a genetic bottleneck in humans. However, some physical evidence disputes the association with the millennium-long cold event and genetic bottleneck, and some consider the theory disproven.

A supervolcano is a volcano that has had an eruption with a volcanic explosivity index (VEI) of 8, the largest recorded value on the index. This means the volume of deposits for such an eruption is greater than 1,000 cubic kilometers.