Lake Toba

Lake Toba lies in the Barisan Mountains of northern Sumatra, Indonesia. Encyclopaedia Britannica reports an area of about 1,140 square kilometres excluding Samosir Island, which occupies a large part of the lake's centre. The International Lake Environment Committee's World Lake Database describes a tectono-volcanic origin, places the lake surface at roughly 905 metres above sea level, and identifies the Asahan River as its outlet.

The lake occupies a large caldera formed by volcanic activity. The Toba Caldera UNESCO Global Geopark describes a super-eruption about 75,000 years ago and identifies Lake Toba as the world's largest volcanic crater lake. Geological accounts describe multiple large eruptive episodes in the region; estimates and reconstructions of their scale depend on geological evidence and methods.

Samosir Island rises within the lake and is a prominent part of its landscape. The caldera and its shores are also a home to Batak communities, including the Batak Toba, whose cultural heritage is represented in local architecture, crafts and traditions. The geopark joins geological interpretation with the region's living natural and cultural heritage.