Rengen is a lake

Lake

A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,...

 on the border between Sweden

Sweden

Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

 and Norway

Norway

Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...

. The 21.49 square kilometres (8.3 sq mi) lake covers 15.72 square kilometres (6.1 sq mi) in Norway and 5.77 square kilometres (2.2 sq mi) in Sweden. The Norwegian part is located in the municipality of Lierne

Lierne

Lierne is a municipality in Nord-Trøndelag county, Norway. It is part of the Namdalen region, and it is the largest municipality in Trøndelag. The administrative centre of the municipality is the village of Sandvika. Other villages include Inderdal, Sørli, and Tunnsjø senter...

 in Nord-Trøndelag

Nord-Trøndelag

is a county constituting the northern part of Trøndelag in Norway. As of 2010, the county had 131,555 inhabitants, making it the country's fourth-least populated county. The largest municipalities are Stjørdal, Steinkjer—the county seat, Levanger, Namsos and Verdal, all with between 21,000 and...

 county, and the Swedish part is located in the municipality of Krokom

Krokom Municipality

Krokom Municipality is a municipality in Jämtland County in northern Sweden. Its seat is located in Krokom.The present municipality was formed in 1974, when the former municipalities of Alsen, Föllinge, Offerdal and Rödön were amalgamated...

 in Jämtland County

Jämtland County

Jämtland County is a county or län in the middle of Sweden consisting of the provinces of Jämtland and Härjedalen, along with minor parts of Hälsingland and Ångermanland, plus two tiny uninhabited strips of Lapland and Dalarna. Jämtland County constitutes 12 percent of Sweden's total area, and is...

. Water flows into Rengen from the lake Ulen

Ulen (lake)

Ulen is a lake in the municipality of Lierne in Nord-Trøndelag county, Norway. The lake lies south of the village of Sørli. Water flows south from the lake Lenglingen into Ulen, and it then continues south into the lake Rengen ....

to the north.