The northern part of Caopatina Lake is crossed to the west by the Opawica River.

The Roy River crosses successively the townships of Chambalon, Pambrun and Hazeur.

The surface of the Roy River is usually frozen from early November to mid-May, however, safe ice circulation is generally from mid-November to mid-April.

The Roy River begins at the mouth of Roy Lake (length: 7.0 kilometres (4.3 mi); elevation: 449 metres (1,473 ft)) in the Township of Chambalon, in Eeyou Istchee James Bay (municipality).

The toponym "Rivière Roy" was officialized on December 5, 1968, at the Commission de toponymie du Québec, when it was created.