Photo by Getty/Last Resort

Oceanic researchers recently recorded sounds from the deepest known spot on the seafloor—Challenger Deep, a valley in the Mariana Trench that plunges nearly seven miles beneath sea level—and, as Gizmodo notes, it turns out to be surprisingly noisy down there. There’s all the whale song, earthquake rumble, and even the sounds of ships and typhoons cutting across the surface of the ocean.

To make the recordings, oceanographer Bob Dziak, of the National Oceanic Atmospheric Administration, designed both a custom ceramic hydrophone (or underwater microphone) capable of withstanding the extreme pressure of those depths and also a mooring system for delivering the device to the seafloor and getting it back up. The sounds they captured are spectacular—though perhaps "spectacular" isn't the right word for a realm that has never seen sunlight. (In fact, Challenger Deep lies more than 10 times deeper than sunlight can penetrate below the ocean's surface.) The moan of a baleen whale makes for a gut-shaking bass glissando, while a seafloor earthquake makes Sunn O))) sound like Alvin and the Chipmunks in comparison.

The sonic potential of the ocean isn't new, of course. Composers, field-recording specialists, and multi-media artists have been exploring deep-sea sounds for decades now. Here are some key milestones—or depth markers, anyway—in the field of subaquatic sound.-=-=-=-

Humpback Whale – Songs of the Humpback Whale (Capitol, 1970)

In the 1960s, the American biologist and environmentalist Roger Payne was the first researcher to discover the complex vocalizations of humpback whales, which communicate in songlike sequences of repeated phrases. His colleagues Scott and Hella McVay used a thermal-printing sonograph to visualize the whales' vocalizations, which, on paper, resembled musical scores.

This 1970 album of his recordings is credited as one of the key catalysts of the Save the Whales movement; The Wire calls it the best-selling nature recording of all time. National Geographic reissued selections from the album on a 1979 flexidisc printed in an edition of 10.5 million. Nearly half a century later, its array of cries and clicks and dolefully harmonized moans, all wreathed in ghostly ambience, still sound like something beamed back from the distant future.

Gavin Bryars – Sinking of the Titanic (Obscure, 1975)