Challenger Deep sits at the bottom of the Mariana Trench, roughly 36,000 feet below sea level. While no light reaches those depths, sound travels very well there. Bob Dziak, an oceanographer at the National Oceanic and Atmospheric Administration (NOAA), recently lead a team that designed and built a special hydrophone that could withstand the immense pressure seven miles below the ocean’s surface. Once the hydrophone was deployed, Dziak and his team recorded for 23 straight days, though they had to wait months for weather and shipping lanes to clear before they could listen to the results of their efforts.
Challenger Deep, it turns out, is an echo chamber for a cacophony of noises produced by everything from ships to baleen whales to Earth itself. In one recording, the researchers even identified the ominous rustling of a category four typhoon whipping across the surface miles above.
A selection of audio clips from Challenger Deep can be heard below.