Laki was the Icelandic volcanic system involved in the massive fissure eruption that began in 1783.
The eruption opened a chain of roughly 140 vents across a fissure about 27 kilometres long in southern Iceland. It continued for around eight months, releasing enormous quantities of lava and volcanic gases. The event is often called the Skaftáreldar, or Fires of the Skaftá River, in Icelandic history.
Sulfur dioxide and other emissions caused severe local pollution and contributed to a haze observed across parts of Europe. In Iceland, poisoned pasture and livestock deaths produced the hardship known as the Mist Hardships. The eruption also affected climate and atmospheric conditions beyond Iceland.
Laki is sometimes called a volcano, but it is more precisely a volcanic fissure or fissure system associated with the Grímsvötn volcanic system. Hekla, Katla, and Eyjafjallajökull are separate Icelandic volcanoes.