Mar Chiquita (in Spanish literally "Little Sea") or Mar de Ansenuza is an endorheic salt lake located in the northeast of the province of Córdoba, in central Argentina. It is the largest of the naturally occurring saline lakes of Argentina.
The lake occupies the southern part of a depression that measures about 80 km (north–south) by 45 km (east–west). Its surface area varies considerably given its shallow depth (about 10 m), between averages of 2,000 and 4,500 km² (corresponding to maximum elevations of between 66 and 69 m above mean sea level). Its center is located approximately at .
Mar Chiquita is fed primarily by the saline waters of the Dulce River, coming from Santiago del Estero in the north after being joined by the Saladillo River. The lands around the lower course of the Dulce and Mar Chiquita are wetlands, populated by a large biodiversity (especially aquatic birds). From the southwest the lake receives (irregularly) the flow of the Primero/Suquía and the Segundo/Xanaes rivers, as well as several streams. The salinity of Mar Chiquita is quite variable, with measured extremes ranging from 250 g/l in times of low water levels to around 40 g/l in very humid years (such as in the 1980s).
There are several islands in the lake, the most important one being the Médano Island (2,000 × 150 m). Mar Chiquita is slowly diminishing in volume due to increased evaporation and elevation of its bottom, and is ultimately bound to turn into a playa (a salt flat).
