It is entirely possible that fish farts may have caused a major diplomatic incident between nuclear superpowers in the 1980s. Russia and Sweden, in truth, almost came to blows over this very thing. At the moment, they just did not know it.

First, some history before we move on to farts. In 1981, on the south coast of Sweden, within 10 kilometers (6.2 miles) from a Swedish naval base, a Soviet submarine crashed. The Soviets believed that serious distress and later navigation mistakes pushed them into Swedish territory, while Sweden saw it as evidence that the Soviet Union was infiltrating Swedish waters at the time. It did not help that when Swedish officials secretly tested gamma-ray spectroscopy for radioactive materials, they found what they were 90% sure was uranium-23 (used for nuclear weapons cladding) within the sub, suggesting that it might be nuclear-armed.

 

The submarine was returned to international waters, but the Swedish government remained alert, persuaded that it was still possible for Russian subs to operate close to its territory. This is when they began to gather enigmatic signals and sounds from underwater. In 1982, for a whole month, several Swedish subs, aircraft, and helicopters followed one of these unidentified sources, only to come up empty-handed.

For over a decade, this persisted. They would search and find nothing but a few bubbles on the sea's surface each time they picked up an acoustic signal. Of course, Sweden was concerned about the intrusions, and could not believe why Russia would try to provoke them in this way, with the Cold War now over.

However, there were farts.

In 1996, a professor at the University of Southern Denmark, Magnus Wahlberg, became interested in the study of unusual signals.

"We were brought into this very secret room under the naval base of Bergen in Stockholm,"We were brought into this very secret room under the naval base of Bergen in Stockholm. "We were sitting there with all these officers and they were actually playing these sounds for us. It was the first time any civilian heard the sound."

When a submarine is detected or even the noise of a propeller, he had expected it to sound like the ping you hear in films.

"It was nothing at all like that said Wahlberg. "It sounded like someone frying bacon. Like small air bubbles releasing underwater."

He and a colleague started the task of finding out what could create bubbles on a scale that would make Sweden believe a nuclear submarine was dealing with it.

"It turns out herring have a swim bladder... and this swim bladder is connected to the anal duct of the fish," Wahlberg said. "It's a very unique connection, only found in herring. So a herring can squeeze its swim bladder, and that way it can blurt out a small number of bubbles through the anal opening."

They let one rip, in layman's words. Herrings swim in enormous schools that can be up to 20 meters (65 feet) deep and span several square kilometers. When they are scared by something near them, such as a starving mackerel school or a submarine searching for Russian spies, they will produce a lot of gas.

Wahlberg bought a herring from a store and applied pressure to test his hypothesis, and, sure enough, it made a sound. He took the video and played it back to the navy staff. It was a great fit for the noise that they had heard.

The good news was that Russia wasn't threatening Sweden, the bad news was that it had been deploying its military for 10 years in search of fish farts. Since they found out what fish farts were and were not, there have been no rumors of aggressive intruders in Swedish waters.