ESSEQUIBO, a river of English Guiana, in South America, which discharges its waters into the Atlantic. Long. 58. 30. W. Lat. 7. N. At its mouth it is twenty miles broad, but of difficult navigation, even for small vessels, on account of the numerous sand-banks which run in different directions across its entrance. There are three islands at the mouth of the river, and for nearly thirty miles upwards there is a succession of islands. The influence of the tide is felt for a hundred miles up the river.