The mainland of Haiti has three regions: the northern region, which includes the northern peninsula; the central region; and the southern region, which includes the southern peninsula. In addition, Haiti controls several nearby islands.
The northern region consists of the Massif du Nord (Northern Massif) and the Plaine du Nord (Northern Plain). The Massif du Nord, an extension of the central mountain range in the Dominican Republic, begins at Haiti's eastern border, north of the Guayamouc River, and extends to the northwest through the northern peninsula. The Massif du Nord ranges in elevation from 600 to 1,100 meters. The Plaine du Nord lies along the northern border with the Dominican Republic, between the Massif du Nord and the North Atlantic Ocean. This lowland area of 2,000 square kilometers is about 150 kilometers long and 30 kilometers wide.
The central region consists of two plains and two sets of mountain ranges. The Plateau Central (Central Plateau) extends along both sides of the Guayamouc River, south of the Massif du Nord. It runs eighty-five kilometers from southeast to northwest and is thirty kilometers wide. To the southwest of the Plateau Central are the Montagnes Noires, with elevations of up to approximately 600 meters. The most northwestern part of this mountain range merges with the Massif du Nord. Southwest of the Montagnes Noires and oriented around the Artibonite River is the Plaine de l'Artibonite, measuring about 800 square kilometers. South of this plain lie the Chaîne des Matheux and the Montagnes du Trou d'Eau, which are an extension of the Sierra de Neiba range of the Dominican Republic.
The southern region consists of the Plaine du Cul-de-Sac and the mountainous southern peninsula. The Plaine du Cul-de-Sac is a natural depression, twelve kilometers wide, that extends thirtytwo kilometers from the border with the Dominican Republic to the coast of the Baie de Port-au-Prince. The mountains of the southern peninsula, an extension of the southern mountain chain of the Dominican Republic (the Sierra de Baoruco), extend from the Massif de la Selle in the east to the Massif de la Hotte in the west. The range's highest peak, the Morne de la Selle, is the highest point in Haiti, rising to an altitude of 2,715 meters. The Massif de la Hotte varies in elevation from 1,270 to 2,255 meters.
The four islands of notable size in Haitian territory are Ile de la Gonâve, Ile de la Tortue (Tortuga Island), Grande Cayemite, and Ile à Vache. Ile de la Gonâve is sixty kilometers long and fifteen kilometers wide. The hills that cross the island rise to heights of up to 760 meters. Ile de la Tortue is located north of the northern peninsula, separated from the city of Port-de-Paix by a twelve-kilometer channel. Ile à Vache is located south of the southern peninsula; Grande Cayemite lies north of the southern peninsula.
Numerous rivers and streams, which slow to a trickle during the dry season and which carry torrential flows during the wet season, cross Haiti's plains and mountainous areas. The largest drainage system in the country is that of the Artibonite River. Rising as the Libón River in the foothills of the Massif du Nord, the river crosses the border into the Dominican Republic and then forms part of the border before reentering Haiti as the Artibonite River. At the border, the river expands to form the Lac de Péligre in the southern part of the Plateau Central. The 400-kilometer Artibonite River is only one meter deep during the dry season, and it may even dry up completely in certain spots. During the wet season, it is more than three meters deep and subject to flooding.