The first recorded audio from the bottom of the Mariana Trench have returned to the surface. Challenger Deep is the deepest known valley on the seafloor and lays at the bottom of the Mariana Trench at 36,000 feet deep.

Bob Dziak, of the National Oceanic and Atmospheric Administration (NOAA), planted a hydrophone in Challenger Deep and recorded audio for 23 days. The pressure at the depth of seven miles under the ocean is an astonishing 16,000 pounds per square inch.

The audio recordings included an earthquake, vocalizing whales, a typhoon and ship noise from the surface, seven miles up.

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