Some vents at the Mariana Trench.
Some vents at the Mariana Trench. USFWS - Pacific Region

Last March, scientists revealed they’d made an astonishing discovery: mysterious and, frankly, kind of terrifying sounds were coming from the Mariana Trench, the deepest part of the world’s oceans. 

At the time, it was just another creepy, odd, vaguely frightening new fact that we learned about the world, with the sources of the sound ranging from ships to whales to dolphins.

But one sound was perhaps the most mysterious of all, three-and-a-half seconds of noise that no one could conclusively identify.

Recently, though, scientists at Oregon State University said they’d found the likely source: minke whales, the smallest of the baleen whales. And while other baleen whale calls had been heard down there, this one in particular was unique. 

“It’s very distinct, with all these crazy parts,” Sharon Nieukirk, a researcher at Oregon State, said. “The low-frequency moaning part is typical of baleen whales, and it’s that kind of twangy sound that makes it really unique. We don’t find many new baleen whale calls.”

Baleen whales typically make the sounds when they mate, meaning that this latest one was likely about sex, too. But scientists won’t be able to positively identify it without further evidence.

“Our hope is to mount an expedition to go out and do acoustic localization, find the animals, get biopsy samples and find out exactly what’s making the sound,” said Nieukirk. “It really is an amazing, weird sound, and good science will explain it.”