Jökulsárlón (Icelandic pronunciation: [ˈjœːkʏlsˌaurˌloun̥] (About this sound listen); literally "glacial river lagoon") is a large glacial lake in southeast Iceland, on the edge of Vatnajökull National Park. Situated at the head of the Breiðamerkurjökull glacier, it developed into a lake after the glacier started receding from the edge of the Atlantic Ocean. The lake has grown since then at varying rates because of melting of the glaciers. It is now 1.5 kilometres (0.93 mi) away from the ocean's edge and covers an area of about 18 km2 (6.9 sq mi). It recently became the deepest lake in Iceland, at over 248 metres (814 ft), as glacial retreat extended its boundaries. The size of the lake has increased fourfold since the 1970s. It is considered as one of the natural wonders of Iceland.

The lake can be seen from Route 1 between Höfn and Skaftafell. It appears as "a ghostly procession of luminous blue icebergs".

Jökulsárlón has been a setting for four Hollywood movies: A View to a Kill, Die Another Day, Lara Croft: Tomb Raider and Batman Begins, as well as the "reality TV" series Amazing Race In 1991 Iceland issued a postage stamp, with a face value of 26 kronur, depicting Jökulsárlón.

The tongue of the Breiðamerkurjökull glacier is a major attraction for tourists.