Lake · Indonesia
Lake Toba
Lake Toba is a huge lake high up in the mountains of the island of Sumatra in Indonesia. It fills the crater of a giant volcano and is the largest volcanic lake in the world.
Picture credit: Lattecupoftea (CC BY 4.0) · Rosmauli tobing (CC BY-SA 4.0) · Herman Kurniawan (CC BY-SA 4.0) · Wikimedia Commons
Where is Lake Toba?
Countries on its shores: Indonesia.
Largest lake of: Indonesia.
Middle of the lake: 2.66° N, 98.90° E
The story behind it
About 74 000 years ago, a supervolcano exploded here in a gigantic eruption. Afterwards the ground sank in and left an enormous hollow, called a caldera, which slowly filled with water. Today the lake lies about 905 metres above sea level and is up to 505 metres deep. It is the largest lake in Indonesia. In the middle rises Samosir, an island of about 647 km². It formed when the ground inside the caldera slowly bulged upwards again. Most people who live around the lake are Batak, and their villages are known for their special traditional houses. Visitors usually arrive in the town of Parapat and cross the water by boat. Only one river, the Asahan, flows out of the lake, and fish that live nowhere else, such as a small fish called Rasbora tobana, swim in its water.
Find it on the globe
Lake Toba is there as a small blue dot with its name, right on the water. From far away the planet is only a blue ball; detail arrives as you zoom in, and this one appears once you are close enough. Open it on the globe.
It sits at its real coordinates, not near them — the same numbers listed in the facts above. Switch off the layer for this kind of place and it disappears again; the buttons for that are down the right-hand edge.
Questions children ask
How big is Lake Toba?
Lake Toba covers about 1 130 km², not counting the big island of Samosir in the middle. That makes it the largest lake in Indonesia.
How did Lake Toba form?
It formed after a supervolcano erupted about 74 000 years ago. The ground collapsed into a giant hollow called a caldera, which then filled with water.
Is Lake Toba the largest lake in Indonesia?
Yes, no other lake in Indonesia is bigger. It is also the largest volcanic lake in the whole world.
Where these numbers come from
Every figure on this page was checked against public reference sources before publication. Where sources genuinely disagree, the text says so.
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