Unidentified submerged objects (USOs) are not as famous as UFOs although they are often encountered, according to declassified Russian Navy records. The common trait of all USO phenomena is that they involve unexplained and technologically advanced objects, far superior to anything we’ve ever built.

The recently declassified documents contain Soviet era reports detailing many cases of possible USO encounters. Former naval officer and Russian UFO researcher Vladimir Azhazha believes these documents are of great value. One of the most interesting cases he examined involved a nuclear submarine on a combat mission in the Southern Pacific. During the routine operation, the submarine detected six unknown objects travelling in formation at speeds in excess of 230 knots (265+ mph). In comparison, the fastest submarine was the Soviet K-222, which reached about 44 knots (51 mph).

The submarine’s sonar determined the objects were heading straight for it so the captain gave the order to surface. The USOs followed them to the surface then flew away. Similar instances have been reported in the region of the Bermuda Triangle, as retired submarine commander Yuri Beketov recalls. On-board instruments often malfunctioned, indicating the presence of strong interference. Many believe this is a clear sign of USO/UFO presence.

On several occasions the instruments gave reading of material objects moving at incredible speed. Calculations showed speeds of about 230 knots, or 265 mph. Speeding so fast is a challenge even on the surface. But water resistance is much higher. It was like the objects defied the laws of physics. There’s only one explanation: the creatures who built them far surpass us in development,” said Beketov.

Both UFOs and USOs seem to concentrate wherever military operations occur, indicating their interest in humanity’s military arsenal.

Another USO hotspot is Lake Baikal in Russia. The world’s deepest freshwater lake has always had a certain mysterious nature and fishermen tell tales of lights being spotted in its deep waters. Multiple folk tales describe swimmers being dragged down by creatures lurking beneath Baikal’s calm waves.

Another of the Russian documents described the encounter between a group of military divers and several humanoid beings in silver suits. The divers were training in Lake Baikal at a depth of 150 feet (50 meters) when they came upon a group of unknown creatures. The divers went deeper in the pursuit of the humanoids. Three men were killed, while the other four were severely injured.

Vladimir Azhazha believes the issue should be thoroughly investigated. “I think about underwater bases and say: why not? Nothing should be discarded,” says Azhazha. “Skepticism is the easiest way: believe nothing, do nothing. People rarely visit great depths. So it’s very important to analyze what they encounter there.”