Lake Malawi

Lake Malawi lies in the southern part of the East African Rift Valley and is shared by Malawi, Mozambique and Tanzania. The names used for the lake vary by country: Lake Malawi in Malawi, Lake Nyasa in Tanzania and Lake Niassa in Mozambique. Encyclopaedia Britannica describes it as the southernmost and third largest of the Eastern Rift Valley lakes.

The elongated lake occupies a fault-bounded rift basin. Its shoreline and catchment cross national borders, and many rivers flow into it. The Shire River is its sole outflow, carrying water south from the lake. International Lake Environment Committee data describe a maximum depth of about 706 metres; lake levels and surface conditions vary with seasonal precipitation and winds.

Lake Malawi is noted for its freshwater fish diversity, particularly cichlids. The UNESCO World Heritage Centre identifies the park at the lake's southern end as globally important for biodiversity and describes hundreds of cichlid species, nearly all endemic to the lake. Freshwater ecoregion assessments likewise report a highly endemic fish fauna. The lake's geographic isolation and varied habitats have contributed to the evolution and diversification of its fishes.

The lake and its basin support communities in all three riparian countries through fisheries and other ecosystem services. A 2023 review in the Journal of Great Lakes Research identifies fishery health, invasive species and climate change among important management concerns, alongside sediment and nutrient pressures. Because the lake is transboundary, research, monitoring and conservation require cooperation among the countries sharing its waters.