Lake Toba lies in the province of North Sumatra on Sumatra, Indonesia.
It was created by the most recent truly large eruption on earth. See toba.
It is the largest lake in Southeast Asia with a surface area of about 1,145 km3. It is also one of the worlds deepest
lakes at 525 m.
Samosir island, in the middle of the lake, is about the same size as Singapore, 530 km3.
It is a very nice place to visit. Attractions in the area include the beautiful Piso-piso waterfall and the chilled out resorts on Samosir's Tuk Tuk peninsula (can you say magic mushroom omelette?), as well as the traditional houses by the Toba Batak people on Samosir island.
Just like in most of Indonesia (whith the exception of Bali), staying here is very cheap. In 2001 you could get a nice, big, clean doubleroom with your own shower and toilet, 2 m from the water for about $1.5 per night.