Lake Matano

Danau Matano is a tectonic lake in a fault trough in South Sulawesi and reaches around five hundred and ninety metres deep, which makes it the deepest lake in Southeast Asia and puts its bottom several hundred metres below sea level - a cryptodepression. It is very old, part of the Malili lake system, and has produced its own endemic fish, shrimps, crabs and snails found nowhere else, which makes it significant to freshwater biologists. It is also clear enough to swim in with visibility of many metres. The complication is industrial: Sorowako on its shore is a nickel mining and smelting town, one of the largest operations of its kind in Indonesia, and the mine, the town and the lake sit together, with the environmental relationship between them long argued over.

What you actually see

• The deepest lake in Southeast Asia - around 590 metres, its floor below sea level.
• Endemic species - fish, shrimps and snails from an ancient isolated lake system.
• Exceptional clarity - swimming with visibility of many metres.
• A nickel town on the shore - Sorowako's mine and smelter beside the water.

When to go

May to September. Two days.

Honest expectations

Sorowako is a company town and some areas are restricted. Access is by small flight or a long road. Facilities are geared to the mine rather than to visitors. The industrial setting is unavoidable.

Nearby

Lake Towuti is the larger neighbour in the same system; Malili is on the coast.