Jökulsá á Fjöllum

Jökulsá á Fjöllum (Icelandic pronunciation: [ˈjœːkʏlsˌauː auː ˈfjœtlʏm] ^ⓘ; "glacial river in the mountains") is the second longest river in Iceland (206 km). Its source is the Vatnajökull glacier. It flows into the Greenland Sea. Jökulsá á Fjöllum streams over the waterfalls Selfoss, Dettifoss, Hafragilsfoss, and Réttarfoss, the second of which is the most powerful waterfall in Europe.

The source of the river is in the Vatnajökull National Park, one of three national parks in Iceland. The river is located in the northeast of Iceland and forms the eastern boundary of Ódáðahraun, an extensive lava field. Its drainage basin is the largest in Iceland at 7,380 square kilometers.