There are plenty of theories about what the USO (unidentified sunken object) might be. Lindberg offered a “new Stonehenge,” though some suspect it’s a natural formation, such as the rim of a small underground volcano, which certainly create a very round, prominent ring.
Others see clear evidence that the object, whatever it is, is too perfectly round to be anything but man-made. Of course, one of the most popular — and most outlandish — theory is that it’s a crashed extraterrestrial spacecraft.
Yet there’s another theory: the USO is neither an extraterrestrial craft nor a natural feature but instead a rotating gun turret from a World War II era battleship. It’s possible that an explosion on the ship’s deck could have blown it out of the deck ring where it was anchored and it slid into the ocean’s depths, more or less intact. Such an explosion would not necessarily have sunk the ship, so the lack of nearby wreckage may not be a mystery.
The turret-less ship might have made it back to port, or may have continued to another location where it eventually succumbed and sank. The top-heavy turret would likely have sunk with the cannons face down in the ocean floor, and would not necessarily have been seen in the sonar image. In fact, Lindberg and his crew were originally drawn to the area in search of Swedish merchant ships sunk by the German navy in World War I.
So what is it? Until someone actually goes down to search the object more closely (or recover it) — a potentially time-consuming and expensive proposition — we may never know. It’s a genuine mystery, and, as is often the case, the most mundane explanation may be the most likely.
Image credit: Ocean Explorer/Peter Lindberg