It extends from southeastern Haiti into the southwestern Dominican Republic, where it is known as the Hoya de Enriquillo.
Covering an area of 28 000 km2 around with a length of 32 km long and 25 km wide,[4] the Plain of the Cul-de-Sac is bounded to the north and south by high mountains and to the west by the Gulf of Gonâve on the edges of which is the Haitian capital of Port-au-Prince and to the Plaine de l'Arcahaie that extends to the west.
[5] This valley was once an arm of the sea and upon withdrawal of the latter during the uprising Oligocene Miocene, salt water was trapped in the lowest points of depression resulting in two grand lakes; Etang Saumâtre (also called "Lake Azuéi") on the Haiti-Dominican Republic border, a small freshwater pond called Trou Caïman in Haiti, and Lake Enriquillo in the Dominican Republic.
Over the decades, this production lost its momentum, giving way to fields of sugar cane.
The Rivière Blanche (Ouest), through its irrigation system and channeling of part of its journey to the Canal Boucanbrou, trickles down this vast plain.