The Waini River is a river in the Barima-Waini region of northern Guyana. It flows into the Atlantic Ocean near the border with Venezuela. It is part of the vast Orinoco River delta swamp forest.

Almond Beach is located at the mouth of the Waini River. It is one of the most important nesting areas for four of the seven species of marine turtles in the world. It is the only place in Guyana that has a large stretch of intact mangrove forests, brackish water and coastal swamp communities.

Santa Rosa is an Amerindian communiy on the Waini River.