Rien is a lake in the municipality of Røros in Trøndelag county, Norway. The  lake is located near the headwaters of the river Glomma, only about  west of the border with Sweden.
Rien is a lake situated within the municipality of Røros in Trøndelag county, Norway. It is near the headwaters of the Glomma river and about west of the border with Sweden.