In November of 2016, the Canadian military began investigating a mysterious sound coming from the bottom of the Arctic.
Inuit hunters were reportedly desperate after the unidentified noise caused sea animals to flee the area.
The sound has been described by locals as a “pinging” emanating from somewhere on the sea floor in the Hecla and Fury Strait...
...but an initial mission by military patrol aircraft conducting an acoustic search failed to detect any anomalies.
A Canadian Department of National Defence spokesman admitted that "the cause of the pings remains mired in mystery"...
During training in 1984, a Navy diver swore he heard a voice ordering “out!”, but did not find his commander when he surfaced.
The only other entity in the tank with him was NOC, a beluga whale trained to retrieve sunken experimental torpedoes.
Several more mystery underwater “conversations” were heard until NOC was identified as the source of the human voice.
The sounds were not natural, and it is believed NOC was mimicking human speech patterns by inflating his nasal cavity.
The phenomenon may also be responsible for other unexplained field reports from divers hearing “screaming children” underwater...
In 1991, scientists recording the sounds picked up on the SOSUS underwater surveillance system detected “Upsweep”...
...an unidentified sound consisting of a “long train of narrow-band upsweeping sounds of several seconds duration each.”
Upsweep is believed to originate from the middle of the Pacific Ocean floor, but its exact location has never been identified.
The US Navy had never seen the signal before, and its “overall source level” has been slowly declining since first contact.
The sound appears to vary with the seasons, but although some theorize it may be volcano activity, it has never been identified.
“Bio-Duck” is the name of a mysterious underwater quacking sound first reported by submarine sailors back in the 1960s.
Soviet submarines were especially wary of the noise, as they believed it may have been a new NATO technology targeting their ships.
Sonar scans, however, always failed to identify any ships, objects, or creatures in the vicinity that could be a source.
Recent research has suggested that it could be from minke whales, but the finding fails to explain the strange Russian encounters...
Deep down 7-miles (11 km) beneath the ocean’s surface, the Mariana Trench is anything but quiet.
In 2015, scientists lowered a microphone to the bottom of the Challenger Deep and made this eerie recording...
...capturing the unearthly moans of a baleen whale just prior to a magnitude 5 earthquake.
Light reaches only about 3,280 feet (1 km) underwater, but sound propagates easily and the microphone could even hear the surface...
...picking up the propeller noise of a passing ship as well as the fury of a category 4 typhoon that churned overhead.