French environmental charity Sea Shepherd created a haunting "sound of the ocean" made up of real-life distress calls from sea creatures—and broadcast from a beacon under the sea.

To highlight the dangers of overfishing, the charity worked with agency TBWA/Paris on the project. It involved French free diver Guillaume Néry, who posted a video of the sound on his various accounts last week claiming to have come across it while diving. The posts prompted speculation online as to what the noise was, but 24 hours later Néry revealed the truth. 

The sound, which was broadcast for two days, was actually coming from a specially designed beacon sunk under the ocean off La Rochelle, where the ship Sam Simon is currently on a mission combating fishing vessels which catch dolphins in their nets. It was created using a combination of different ocean sounds including a harpooned whale, pilot whales hunted down in the Faroe Isles, dolphins caught in fishermen's nets and agitated schools of fish packed together in trawlers’ nets.