Lake Tsimanampetsotsa () (also called Lake Tsimanampesotse) is a moderately alkaline lake in the Toliara Province, in the southwestern part of Madagascar. It is located at around . The lake is protected within Tsimanampetsotsa National Park and it is also within a Ramsar site. The Ramsar site has a total area of , while the surface of the lake is much smaller. The name of the lake in Malagasy means "lake without dolphins". It is a sacred place for worship, ceremonies and rituals. Local taboos prevent water pollution. Swimming and the utilisation of pirogues is prohibited. Water, mud and some plants from the lake are used in traditional medicine (Tahirindraza and Marikandia 2015). The lake is about 20 km long, about 2 km wide and is quite shallow (maximum depth about 2 m). It is situated in a collapse area of the Mahfaly Plateau, in a closed evaporite basin with cliffs of Eocene marine limestone to the east and a wide strip of alluvium, capping low outcrops of limestone to the west. The area is covered by sand deposits of recent and Quaternary origin. In pre-history, there was a paleolake here complete with overland drainage (deltaic sediments laid down by a paleodrainage system have been found). The paleolake was much greater in size and depth, as evidenced by strand lines that ring the outer edges of the basin. The water is “sodic”, highly mineralised and moderately alkaline (pH ~ 8.0) with relatively high concentrations of ammonia and phosphate. Salt concentrations approach that found in seawater, becoming somewhat diluted during the rainy season. The lake may be directly connected to the sea, but this is a matter of conjecture that has not been verified. The eastern part of the lake receives some freshwater flow and so has consistently lower salt concentrations than the western part. The basin is shallow resulting in dramatic variation in the surface area of the lake with even small changes in water level. Water levels can drop significantly during the dry season, resulting in a broad exposed area of seasonal hypersaline flats around a shrunken lake. Climate and Hydrology Lake Tsimanampetsotsa is in an area with a semi-arid climate; daytime temperatures are high and precipitation low. It is in the lowest precipitation region in Madagascar, receiving only 300 mm of rain per year. In addition, rainfall amount and location is highly unpredictable; rain often falls only locally.