While many think of space as the “undiscovered country,” Earth’s oceans are unknown to us, too. Now, scientists have listened in on the deepest, most unexplored part of our oceans — the Mariana Trench — and it’s a noisy place.
The team of scientists from Oregon State University put a titanium-cased hydrophone at the deepest point and recorded the ambient noise of the trench for three weeks.
“You would think that the deepest part of the ocean would be one of the quietest places on Earth,” said Robert Dziak, a NOAA research oceanographer and chief scientist on the project. “Yet there really is almost constant noise from both natural and man-made sources.”
Dziak said the sound of nearby and distant earthquakes could be picked up along with “distinct moans of baleen whales and the overwhelming clamor of a category 4 typhoon that just happened to pass overhead.”
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Ship traffic going between Guam, China and the Philippines could also be picked up.
The project was quite the undertaking: the scientists had only ever put a hydrophone 1.6 km deep.
“It is akin to sending a deep-space probe to the outer solar system,” Dziak said. “We’re sending out a deep-ocean probe to the unknown reaches of inner space.”
The Mariana Trench is in the western Pacific Ocean, east of the Philippines. It stretches for about 2,550 km and is about 69 km wide. The Challenger Deep is about 11 km and the deepest part of the ocean on Earth. To put it in perspective, if you dropped Mount Everest into it, there would still be a 1.6 km space above.