Lake Enriquillo (Spanish: Lago Enriquillo) is a hypersaline lake in the Dominican Republic located in the southwestern region of the country. Its waters are shared between the provinces of Bahoruco and Independencia, the latter of which borders Haiti. Lake Enriquillo is the largest lake in both the Dominican Republic and Hispaniola, as well as the entire Caribbean. It is also the lowest point for an island country.

Lake Enriquillo covers an area of 380 km² (150 sq mi), and is the lowest point for an island country, falling 46 m (151 ft) below sea level. Its drainage basin includes ten minor river systems. The rivers that rise in the Neiba Mountains to the north (lower center and lower right of the image) are perennial. Those rivers that rise in the Baoruco Mountains to the south are intermittent. Lake Enriquillo has no outlet, making it an example of an endorheic lake. The lake's water level varies because of a combination of storm-driven precipitation events and the region's high evaporation rate. Salinity in the lake can vary between 33 parts per thousand (comparable to seawater) and over 100 parts per thousand (hypersaline).

The region has a hot, semiarid climate. Annual rainfall is not evenly distributed, with peak precipitation occurring in May and October. The dry season is December through April when rainfall may be less than 20 mm (0.79 in). Due to the length of the lake, annual rainfall averages also vary at the eastern and western ends: 729 mm (28.7 in) on the northwest shore, and 508 mm (20.0 in) in the southeast.

Between 2004 and 2009, the lake doubled its surface area. Records for 2004 show the lake to be 164 km² (63 sq mi); measurements from 2011 put the area at 350 km² (140 sq mi).

Reasons for the flooding are being debated, but may be a combination of several, including increases in rainfall in the region in recent years, increase of sediments going into the lake from run-off due to deforestation that are contributing to raising the lakebed, and milder temperatures, which are reducing the surface evaporation rate.

The lake lies in a valley that stretches from near Port-au-Prince in Haiti to Bahia de Neiba in the Dominican Republic. The valley is known as the Hoya de Enriquillo in the Dominican Republic and as the Plain du Cul-de-Sac in Haiti. Parts of the depression are below sea level and are covered by large salt lakes, including Lake Enriquillo and Etang Saumâtre, Hispaniola's second largest lake (as well as Haiti's largest).

There historically were three islands in the lake: Barbarita, Islita, and Isla Cabritos. Once, when water levels dropped during dry spells, the islands were linked to one another by sandbars. As of December 2011, only Isla Cabritos remains; the other two islands were submerged by the rising levels of the lake.

Lake Enriquillo is located within a linear depression that formed as a ramp basin between the Haiti fold and thrust belt to the north and the uplifted oceanic crust of the Massif de la Selle and Sierra de Bahoruco mountain ranges to the south. The Enriquillo-Plantain Garden fault is a later strike-slip fault, cutting across the depression, which extends from Jamaica in the west to near Neiba in the Dominican Republic in the east. The valley, a former marine strait, was created around one million years ago when the water level fell and the strait was filled in by sediments of the Yaque del Sur River. Due to this, tremors in the region are common.