The Dominican Republic occupies the eastern two-thirds of Hispaniola, the second-largest island in the Caribbean after Cuba. The country covers approximately 48,671 square kilometers, sharing a 376-kilometer land border with Haiti to the west. The Atlantic Ocean bounds the northern coast across roughly 586 kilometers, while the Caribbean Sea defines the southern shoreline for approximately 545 kilometers. This dual-coast positioning creates distinct maritime environments that influence both climate patterns and coastal ecosystems. The Mona Passage, a strait approximately 130 kilometers wide, separates the Dominican Republic from Puerto Rico to the east and serves as a major shipping channel between the Atlantic and Caribbean basins.
The Cordillera Central dominates the interior landscape, running northwest to southeast through the heart of the country for approximately 250 kilometers. This range contains Pico Duarte, which reaches 3,087 meters above sea level and stands as the highest point in the Caribbean. The summit temperature averages between 5 and 12 degrees Celsius year-round, and nighttime frost occurs regularly above 2,500 meters even during summer months. Four major river systems originate in the Cordillera Central. The Yaque del Norte River extends 308 kilometers from Pico Duarte northwest to Monte Cristi on the Atlantic coast, making it the longest river in the country. The Yaque del Sur flows 183 kilometers southward to Bahía de Neiba. The Yuna River drains 209 kilometers eastward into Samaná Bay, while the Artibonito River forms part of the border with Haiti before entering Haitian territory entirely.
North of the Cordillera Central lies the Cordillera Septentrional, a coastal mountain range running parallel to the Atlantic shoreline for approximately 175 kilometers from Monte Cristi eastward to the Samaná Peninsula. This range reaches maximum elevations near 1,200 meters and creates an orographic barrier that generates heavy rainfall on windward slopes. Between these two mountain systems lies the Cibao Valley, an elongated lowland stretching roughly 240 kilometers from northwest to southeast. The valley floor sits between 100 and 300 meters elevation and constitutes the most agriculturally productive region in the country, particularly for rice, tobacco, and cacao cultivation. Annual rainfall in the Cibao Valley ranges from 1,000 to 1,500 millimeters, with pronounced wet seasons from May through June and October through November.
The Sierra de Bahoruco rises in the southwest, extending from the Haitian border eastward for approximately 80 kilometers with peaks reaching 2,367 meters at Loma del Toro. This range exhibits a rain shadow effect that creates arid conditions on its northern slopes. Directly north of the Sierra de Bahoruco lies Lake Enriquillo, a hypersaline lake sitting 46 meters below sea level at its lowest recorded point, making it the lowest elevation in the Caribbean. The lake has historically fluctuated in size, expanding from approximately 200 square kilometers in 2004 to over 350 square kilometers by 2013 due to increased rainfall and reduced evaporation, flooding several lakeside communities. Water salinity in Lake Enriquillo measures approximately 100 parts per thousand, roughly three times the salinity of seawater, supporting a unique population of American crocodiles and ricord iguanas. Isla Cabritos, an elongated island in the lake, forms part of Lago Enriquillo e Isla Cabritos National Park.
The Samaná Peninsula extends approximately 60 kilometers eastward from the mainland into the Atlantic Ocean, creating Samaná Bay on its southern shore. The peninsula reaches widths between 15 and 20 kilometers and consists primarily of karst limestone formations with elevations generally below 600 meters. Los Haitises National Park occupies the southwestern shore of Samaná Bay, covering approximately 1,600 square kilometers of karst topography characterized by conical hills called mogotes rising 30 to 40 meters above mangrove forests. The park receives between 2,000 and 2,500 millimeters of annual rainfall, supporting subtropical moist forest that contains over 700 plant species. Samaná Bay itself measures approximately 60 kilometers east-west and 18 kilometers north-south, serving as a breeding ground for humpback whales from mid-January through late March annually.
The southeastern coastline features extensive limestone platforms and coral reef systems. Saona Island lies approximately 800 meters off the mainland coast, measuring roughly 22 kilometers long and 5 kilometers wide at its broadest point. The island forms part of Del Este National Park, which encompasses 420 square kilometers of marine and terrestrial ecosystems including extensive seagrass beds that support manatee populations. Catalina Island, located approximately 2 kilometers offshore from La Romana, covers roughly 15 square kilometers and remains uninhabited except for day tourism operations. Beata Island sits in the Caribbean Sea approximately 7 kilometers southwest of the mainland Pedernales Peninsula, covering 27 square kilometers with elevations reaching 15 meters.
The southwestern coast contains Jaragua National Park, the largest protected area in the country at approximately 1,400 square kilometers combining terrestrial and marine zones. The park includes Bahía de las Águilas, an 8-kilometer beach considered among the most isolated coastal areas in the country, accessible only by boat or four-wheel-drive vehicles over rough mountain tracks. The coastal waters around Jaragua support significant seabird populations including brown pelicans, magnificent frigatebirds, and sooty terns, with breeding colonies on offshore cays. The terrestrial sections of the park exhibit xerophytic scrub vegetation adapted to annual rainfall below 600 millimeters and temperatures regularly exceeding 35 degrees Celsius during summer months.
Climate across the Dominican Republic varies primarily by elevation and exposure to prevailing northeasterly trade winds. Coastal lowlands along both the Atlantic and Caribbean shores experience tropical wet-dry conditions with temperatures averaging 25 to 28 degrees Celsius year-round and minimal seasonal variation. Santo Domingo, situated on the Caribbean coast at approximately 14 meters elevation, records average high temperatures of 30 to 32 degrees Celsius throughout the year with average lows between 20 and 23 degrees Celsius. Annual rainfall in Santo Domingo averages approximately 1,400 millimeters, with May and October typically receiving the highest monthly totals of 180 to 200 millimeters each, while January through March average 50 to 70 millimeters monthly.
The northern coast receives substantially more precipitation due to orographic lifting as trade winds ascend the Cordillera Septentrional. Puerto Plata averages approximately 2,200 millimeters of rainfall annually, with October through January each recording monthly totals between 200 and 280 millimeters. Temperatures in Puerto Plata mirror southern coastal patterns, though nighttime lows average 1 to 2 degrees Celsius cooler due to elevation and Atlantic exposure. The Samaná Peninsula receives the highest rainfall totals in the country, with some mountainous areas recording over 3,000 millimeters annually. Sánchez, on the southern shore of Samaná Bay, averages approximately 2,400 millimeters of rain per year with no true dry season, though February through April receive the lowest monthly totals of 80 to 120 millimeters.
Interior mountain valleys exhibit microclimates substantially cooler than coastal areas. Constanza, situated in the Cordillera Central at approximately 1,200 meters elevation, records average temperatures between 18 and 24 degrees Celsius year-round, with nighttime lows occasionally dropping to 5 degrees Celsius during December through February. Annual rainfall in Constanza averages approximately 1,000 millimeters, lower than coastal areas despite higher elevation due to rain shadow effects from surrounding peaks. The Constanza valley produces temperate-climate vegetables including strawberries, lettuce, and potatoes that cannot be grown economically in lowland areas. Jarabacoa, located at approximately 500 meters elevation in the Cordillera Central, maintains average temperatures between 22 and 28 degrees Celsius with annual rainfall near 1,200 millimeters.