Researchers have lowered a microphone underwater and recorded ambient noises from the deepest known trench in the Earth’s seabed, the Challenger Deep in the western Pacific Ocean. The BBC reports: For the first time, scientists have obtained audio recordings from 7 miles (11km) below sea level in Challenger Deep, the deepest part of the Mariana Trench, south-west of Guam. They reveal a soundscape rich with the rumble of earthquakes, the deep moans of whales – and the mechanical whirr of ships. The recordings were made by researchers from the National Oceanic and Atmospheric Administration, Oregon State University and the US Coast Guard as part of an effort to measure the amount of sound pollution in the Pacific Ocean. You can listen to some of the recordings below. “Noise in the ocean has been increasing in the last few decades because of a growth in container shipping,” says Robert Dziak, the NOAA oceanographer who led the project. “Many researchers are now recognising that this can have an effect on marine ecosystems.” Exactly how much of an effect, though, is unclear – partly because we do not know how bad the sound pollution is. “There are sensors out there to monitor the [...]