River, east-central Guyana.
The largest river between the Amazon and the Orinoco rivers and the longest in Guyana, it rises in the Acarai Mountains on the Brazilian border. It flows north for about 630 mi (1,000 km) to empty into the Atlantic Ocean 13 mi (21 km) from Georgetown . Its estuary, 20 mi (32 km) wide, is obstructed by islands and silt but is navigable by small ocean vessels to Bartica, 50 mi (80 km) inland.