Lake Maninjau, Volcanic crater lake in West Sumatra, Indonesia.

Lake Maninjau is a volcanic crater lake in West Sumatra surrounded by steep rocky walls that rise directly from the water. The basin spans a large area with considerable depth in places.

The Maninjau caldera formed about 52,000 years ago in an eruption that spread 220–250 cubic kilometres of pyroclastic material over more than 8,500 square kilometres. The collapse left a basin 20 km long and 8 km wide, later filled by a lake 16 km long and 7 km wide. Local legend links the water to the tale of Bujang Sembilan.

The name Maninjau means "overlook" or "observation" in the Minangkabau language. Local tradition links the lake to the story of Bujang Sembilan. Two endemic foods are gathered here: pensi, a small mussel, and palai rinuak, a small fish grilled with coconut and spices and wrapped in a banana leaf.

From Bukittinggi, the road descends to the lake via Kelok 44, a 10 km stretch of 44 hairpin bends between Ambun Pagi and Maninjau. The steep grade and tight turns call for low gears and careful braking. The lake lies at 459 m above sea level, so the air is cooler than on the coast.

The lake's name means "overlook" or "observation" in Minangkabau. In early June 1948, Indonesia's first president, Sukarno, visited and wrote a pantun urging travellers not to come to Ranah Minang without stopping at Maninjau.