Baltic Sea anomaly

[6] According to the team, they returned from an expedition in the Baltic Sea between Sweden and Finland with a "blurry but interesting" sonar image while searching for an old shipwreck in the summer of 2011.

[3] Swedish geologists Fredrik Klingberg and Martin Jakobsson say that the chemical composition of the samples provided resembles that of nodules that are not uncommon in sea beds, and that the materials found, including limonite and goethite, can indeed be formed by nature itself.

[3] Hanumant Singh of the Woods Hole Oceanographic Institution has said that it cannot be trusted because several distortions render it "virtually useless for identifying an undersea formation".

"[4] Reacting to a photo published by Swedish newspaper Expressen purportedly taken by OceanX during a dive to collect rock samples, Göran Ekberg, a marine archaeologist at Maritime Museum in Stockholm, said: "A natural, geological formation can't be ruled out.

[3] According to Finnish planetary geomorphologist Jarmo Korteniemi, volcanic-based explanations such as a hydrothermal vent are not plausible on the Fennoscandian shield as it is a thick craton with no active volcanism after the Proterozoic,[10] and regional bathymetry explains the "runway" formation under the anomaly as part of a larger group of similar NNW-SSE oriented mounds which occur located on the bottom of the Bothnian Sea.

[5][12] Jonathan Hill of the Mars Space Flight Facility questioned the motives involved in OceanX announcements, which included plans to take wealthy tourists in a submarine to visit the site.