Lake Poso, Freshwater lake in Central Sulawesi, Indonesia

Lake Poso is a large freshwater body in Central Sulawesi surrounded by forested hills and green shorelines dotted with small villages and fishing settlements. The water appears calm and clear, with steep slopes descending into the deeper parts.

Europeans only heard reports of a large lake in the Poso interior until 1865, when Manado official J. C. W. D. A. van der Wyck reached it and mapped it roughly. Willem Jan Maria Michielsen followed in 1867 with another imperfect sketch. The lake lies at 600 m elevation, measures 32 km by 16 km, and reaches 384.6 m deep.

Communities living around the lake have fished these waters for generations and grow rice, cloves, and vanilla on the surrounding land. These activities shape daily life and connect people to the water in practical ways.

The lake drains into the Poso River at Tentena in the north, which flows to the town of Poso on the Molucca Sea; Pendolo lies at the southern end. Water levels are managed for the Poso 1 hydropower dam, with the surface averaging 511.7 m above sea level and a low point of 509 m, so shoreline conditions vary.

The lake is home to fish species and freshwater snails found nowhere else in the world, making it a natural laboratory for studying evolution. Scientists continue to discover and study these isolated creatures that live only in these waters.