In 2008 a Norwegian-lead expedition to the seafloor of the Mid-Atlantic Ridge between Greenland and Norway brought to light an extraordinary finding: The northernmost deep-sea hydrothermal vents within the Arctic Circle. Dissolved sulfide minerals that solidify when vent water as hot as 300 °C (570 °F) hits the icy cold of the deep sea have, over the years, accumulated around the vent field in what is one of the most massive hydrothermal sulfide deposits ever found on the seafloor. The accumulation of the chimneys assembles the shape of a fantasy castle what led the scientists the name it Loki's Castle, referring to a Norwegian god renowned for trickery.
At a depth of around 2,352 metres (7,717 ft) the cluster of five hydrothermal vents, also called black smokers, the whole deposit is about 250 metres (825 ft) in diameter at its base and about 90 metres (300 ft) across on the top and might turn out to be the largest such deposit seen on the seafloor. Given the massive sulfide deposit, the vent field must surely have been active for many thousands of years.
The more spectacular findings, however, is that scientists discovered a new group of Archaea, the Lokiarchaeota (or "Loki" for short), and identify it as a missing link in the evolutionary lineage of eukaryotes or all complex cell organisms. In this context, the discovery of the Lokiarchaeota, with some but not all of the characteristics of eukaryotes, provides evidence on the transition from archaea to eukaryotes. Because of that, some scientists think the vents would have been great locales for the origin of life on Earth.