Rostojávri is the Sami name for the Rostavatn lake on the border between 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...

 and 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....

. The Norwegian name for the lake is Rostavatn and the Swedish name is Råstojaure. The lake is located in the municipality of Målselv

Målselv

Målselv is a municipality in Troms county, Norway. The administrative centre of the municipality is the village of Moen. Some other villages include Andslimoen, Bardufoss, Alappmoen, Holmen, Fossmoen, and Heggelia...

 in county Troms

Troms

or Romsa is a county in North Norway, bordering Finnmark to the northeast and Nordland in the southwest. To the south is Norrbotten Län in Sweden and further southeast is a shorter border with Lapland Province in Finland. To the west is the Norwegian Sea...

 on the Norwegian side of the border, and in municipality Kiruna

Kiruna

Kiruna is the northernmost city in Sweden, situated in Lapland province, with 18,154 inhabitants in 2005. It is the seat of Kiruna Municipality Kiruna (Northern Sami: Giron, Finnish: Kiiruna) is the northernmost city in Sweden, situated in Lapland province, with 18,154 inhabitants in 2005. It is...

 in county Norrbotten

Norrbotten

Norrbotten is a Swedish province in northernmost Sweden. It borders south to Västerbotten, west to Swedish Lapland, and east to Finland.- Administration :...

on the Swedish side.
The lake lies at 680m and covers an area of 34.24 km - 3,67 of which is in Norway and 30.57 in Sweden.