A new cold seep, southwest of Svalbard

West of Svalbard, several cold seeps are well known and described such as the Vestnesa Ridge and its large pockmarks which have been known for decades. Many seeps have also been found in various areas on the continental shelf west of Svalbard, but without specific morphological signatures. In 2017, a conspicuous seafloor structure at 800 m depth, caught our attention. The structure had a crater-like feature in its center, with adjacent ridges. A first sub-bottom profiler line was acquired the same year, indicating a possible seep. In 2019, a first video transect confirmed the presence of extensive microbial mats and carbonate crusts, indicating an active methane seep. Finally in 2022, eight more video transects allowed an extensive morphological study of the structure. Together with bacterial mats and carbonate crusts, small sediment mounds, domes often covered by microbial mats, and hummocky seafloor colonised by siboglinid tubeworms cover large areas of the structure. These features are linked to different stages of seepages, some of them active and others either dormant or extinct. Examples of observed active seepages are free gas bubbles flowing from a broken carbonate crust at the center of the structure, and plumes close to its eastern limit. Thick carbonate crusts indicate a long seepage history in the center of the structure and on top of the ridges. The sources of the seeps are likely to be Miocene old organic-rich deposits, or Paleocene hydrocarbon reservoirs.