The principal range of mountains runs from west to east. The rivers, which traverse their slopes, generally flow north or south.
Most of the rivers in Jamaica are not navigable. The height of the mountains causes them to run swiftly in deep beds, and their courses are sometimes broken by waterfalls. One exception is the Black River, the largest river in Jamaica. It is 73 kilometers (44 miles) long, and for 28 kilometers (17 miles) from its mouth it is navigable for small vessels.
The rivers of Portland, which have their source in the Blue Mountains, flow very swiftly, and can be very destructive in time of heavy rainfall. The Rio Grande, rising on the northern slopes of the Blue Mountains, is a large river which has its course through some of the wildest and most beautiful scenery in the island. Rafting on this river has become, in recent years, a popular sporting pastime. Other main rivers of Portland are the Swift, Spanish, and Buff Bay.
The Wag Water (formerly Agua Alta) rises in the mountains of St. Andrew and flows through the parish of St. Mary, entering the sea west of Annotto Bay. The Hope River rises in the hills near Newcastle and enters the sea about 10 kilometers (6 miles) east of Kingston. Both the Wag Water and the Hope river supply Kingston with water.
The Milk River, which is navigable for some 3 kilometers (2 miles), supplies a system of canals for the irrigation of the plains of Vere in Clarendon. Rising at Windsor in the interior of Trelawny, the Martha Brae discharges to the east of Falmouth. The chief river of Westmoreland, the Cabaritta, waters the alluvial district of the area.
With its tributaries rising in the Above Rocks district in St. Andrew, the Rio Cobre runs through St. Catherine, and is used for providing irrigation and drinking water. The Plantain Garden River in St. Thomas is the only important river which does not follow the general rule of flowing north or south. Flowing south in its upper course, it turns east upon meeting the coastal range of hills. It then flows through the fertile Plantain Garden River Valley and enters the sea at Holland Bay.
Special mention must be made of the underground rivers in the limestone region. The Cave and Hectors Rivers are notable examples. The porous nature of the limestone accounts for the scarcity of water in the central districts. The parish of St. Ann, because it is chiefly of limestone formation, has no rivers in its interior. When swollen by exceptional rainfall the underground reservoirs sometimes rise to the surface as lakes. The Moneague Lake near Moneague last rose in 1970 and disappeared in 1971.
|Rivers||Length||Parish||Direction of Flow|
|Hope River||19.6km / 12.2mi||St. Andrew||South|
|Morant River||25.9km / 16.1mi||St. Thomas||South-East|
|Plantain Garden River||34.9 / 21.7mi||St. Thomas||South at source then east|
|Yallahs River||36.9km / 22.9mi||St. Thomas||South|
|Buff Bay River||22.2km / 13.8mi||Portland||North|
|Hector's River||5.1km / 3.2mi||Portland||North-East|
|Rio Grande||34.3km / 21.3mi||Portland||North|
|Rio Nuevo||24.0km / 14.9mi||St. Mary||North|
|Wag Water River||36.2km / 22.5mi||St. Mary||North|
|White River||27.4km / 17mi||St. Ann||North|
|Martha Brae River||32.5km / 20.2mi||Trelawny||North|
|Great River||46.0km / 28.6mi||St. James||North|
|Montego River||24.1km / 15mi||St. James||North|
|Lucea West River||14.0km / 8.7mi||Hanover||North|
|Lucea East River||12.9km / 8mi||Hanover||North|
|Cabaritta River||39.7km / 24.7mi||Westmoreland||South|
|Deans Valley River||17.1km / 10.6mi||Westmoreland||South|
|Negril River||15.3km / 9.51mi||Westmoreland||West-South-West|
|Black River||53.4km / 33.2mi||St. Elizabeth||South|
|Milk River||36.4km / 22.6mi||Clarendon||South|
|Rio Minho||92.5km / 57.5mi||Clarendon||South|
|Rio Cobre||50.9km / 31.6mi||St. Catherine||South|