For 15 years, Sweden believed Russian submarines were invading their territory. The disturbances that were detected in the ocean led to some tense times and almost brought the countries to the brink of war, but in actuality, they were just Herring farts.

Quick history recap:

In 1981, a Soviet submarine ran around on the coast of Sweden (a mere 6 miles from a Swedish naval base). The Soviets claimed they were in severe distress due to navigation issues but Sweden was pretty convinced it was proof that the Soviet Union was infiltrating Swedish waters. Also, it didn't help that Swedish officials secretly measured radioactive materials and were 90% positive that they had detected uranium inside the sub.

The Soviet sub returned to international waters, but the Swedish government remained convinced that the vessel remained close by. In 1982, Sweden's own subs and naval boats started picking up mysterious underwater signals and sounds from the area, yet found no sign of the Soviet ship. This continued on for over a decade and Sweden didn't understand why, with the Cold War being over, Russia would continue to taunt them.

In 1996, Magnus Wahlberg (no relation to Marky-Mark), a professor at the University of Southern Denmark, joined the investigation of the mysterious signals. He and a colleague were tasked with figuring out what the Peter Heck was making these sounds so similar to a nuclear submarine.

Wahlberg describes his experience on a 2012 Ted Talk:

"We were brought into this very secret room under the naval base of Bergen in Stockholm with all these officers and they were actually playing these sounds for us. It was the first time any civilian heard the sound, it sounded like someone frying bacon. Like small air bubbles releasing underwater."

Wahlberg quickly discovered that the sound was coming from a Herring fart. Herrings are a unique fish that have a swim bladder which is connected to the anal duct. Herrings squeeze their swim bladder and blurt out bubbles through the anal opening, i.e. "Let 'Er Rip."

Herring swim in gigantic schools and when something frightens them, they generate a lot of gas.

Good news here is that the threat from Russia was just farting fish, bad news is that they spent a lot of time and money in pursuit of fish farts.

Wahlberg believes that a major diplomatic incident between nuclear superpowers could have been triggered by these fish farts. They just didn't know it at the time.