For what may be the first time, NOAA and partner scientists eavesdropped on the deepest part of the world's ocean and instead of finding a sea of silence, discovered a cacophony of sounds both natural and caused by humans.
For three weeks, a titanium-encased hydrophone recorded ambient noise from the ocean floor at a depth of more than 36,000 feet, or 7 miles, in the Challenger Deep trough in the Mariana Trench near Micronesia. Researchers from NOAA, Oregon State University, and the U.S. Coast Guard were surprised by how much they heard.