A long-term underwater observatory has been deployed at Ultima Thule, a newly discovered hydrothermal vent site in the Arctic Ocean. The deployment was carried out by the Swedish icebreaker Oden during its Canada–Sweden Arctic Ocean 2025 expedition, with financing from the GoNorth 2025expedition.
The decision to carry out the deployment with Oden was taken early in the planning process: with GoNorth 2025 scheduled to begin at the end of November, the heavy ice conditions likely to be encountered at that time brought a lot of uncertainty. Oden was scheduled to be in the same region in August–September, so it was agreed that the ship would handle the deployment.
A new tool for studying a unique Arctic vent field
The observatory, part of the national infrastructure NOR-EMSO, consists of a lander and a mooring line equipped with sensors to record ocean conditions over time. It includes three Conductivity, Temperature and Depth (CTD) sensors, nine temperature sensors, and a high-accuracy pressure sensor. Together, they will provide continuous measurements of water properties close to a hydrothermal system located deep on the Arctic seafloor.
The data will help improve our understanding of how heat, minerals, and chemical compounds spread through the deep ocean environment. This information is of interest to anyone studying the geology and biology of hydrothermal systems, which host unique ecosystems based on chemical energy rather than sunlight.
From discovery to long-term monitoring
The observatory is the latest step in research that began with the discovery of the Ultima Thule vent field during GoNorth 2023, the second expedition of Norway’s GoNorth programme. That year, the research vessel Kronprins Haakon located active hydrothermal vents in the Lena Trough, a mid-ocean ridge between Svalbard and Greenland.
Among the discoveries were shimmering vents and, most importantly, an active “black smoker” chimney estimated to be up to ten metres tall. These sites lie on Lucky Ridge, a 1600-metre-high subsea mountain rising from a 4000-metre-deep valley. The unique geology of Lucky Ridge makes it an extraordinary natural laboratory for studying the interplay between seawater, mantle rocks, and life.
“Ultima Thule has many characteristics that set it apart from other vent fields,” said expedition leader Rolf Birger Pedersen after the 2023 discovery. “It is likely to become an important site for international research.”
