A blackwater river is a river with a deep, slow-moving channel flowing through forested swamps or wetlands.
Blackwater River may also refer to:
Canada
West Road River (also Blackwater River), a major tributary of the Fraser River
Great Britain
England
Blackwater River (River Axe), a tributary of the River Axe in Devon and Dorset
River Blackwater, Essex
Blackwater Estuary
River Blackwater (River Loddon), a tributary of the Loddon forming boundaries of Hampshire with Surrey and Berkshire
River Blackwater (River Test), a tributary of the Test in Wiltshire and Hampshire
Scotland
Black Water (Conon), in Wester Ross, Scotland
Ireland
Blackwater River, a distributary of the River Shannon
Enfield Blackwater, flowing from Staplestown, County Kildare, to the River Boyne in County Meath
Kells Blackwater also known as Leinster Blackwater, flowing from Lough Ramor, County Cavan, to Navan, County Meath
Kerry Blackwater, a river in County Kerry
Kilkenny Blackwater, a tributary of the River Suir in County Kilkenny
Munster Blackwater, a river which flows through Counties Kerry, Cork, and Waterford
River Blackwater, County Cavan
Ulster Blackwater in Counties Armagh, Tyrone and Monaghan
New Zealand
Blackwater River (Tasman), a tributary to the Mangles River
Blackwater River (Buller River tributary)
Blackwater River (Little Grey River tributary)
United States
Blackwater River (Perdido River tributary), a river in Baldwin County, Alabama
Blackwater River (Florida), a river arising in southern Alabama and flowing through the Florida Panhandle to the Gulf of Mexico
Blackwater River (Maine), a river in Aroostook County
Blackwater River (Maryland), a largely saltwater river in Dorchester County
Little Blackwater River (Maryland), a tributary
Blackwater River (Massachusetts–New Hampshire), a tidal inlet in northeastern Massachusetts and southeastern New Hampshire
Blackwater River (Missouri), a tributary of the Lamine River
Blackwater River (Contoocook River tributary), a river in central New Hampshire
Blackwater River (Virginia), a river in southeastern Virginia
Blackwater River (West Virginia), a river in the Allegheny Mountains (with a tributary named Little Blackwater River)