A real sonar anomaly, best explained as glacial geology
In 2011 a Swedish salvage team scanning the Gulf of Bothnia floor got a sonar return of a large circular object with what looked like ramps and right angles, and the internet promptly decided they had found a crashed flying saucer. Geologists who examined the samples the divers brought up identified glacial rock, most likely a moraine deposit dropped by the retreating ice sheet. A good reminder that the sea floor is genuinely unexplored and that most anomalies are geology. Told honestly.
The northern Baltic Sea (Swedish waters)
See it on the map
Other places on the map within a couple of hours of here.
