The US Coast Guard has released a haunting audio of what is believed to be the acoustic signature of the 2023 Titan submersible implosion.

The audio was captured by a National Oceanic and Atmospheric Administration moored passive acoustic recorder, approximately 1450km from the implosion site, the Coast Guard said.

On an expedition to the Titanic shipwreck, the Titan imploded on June 18, 2023. The five passengers aboard were all confirmed dead following the discovery of the wreckage.

The passengers were Stockton Rush, the founder and CEO of OceanGate; businessman Shahzada Dawood and his 19-year-old son, Suleman Dawood; businessman Hamish Harding; and French diver Paul-Henri Nargeolet.

The audio released Tuesday by the Coast Guard’s Marine Board of Investigation is part of an ongoing investigation into OceanGate, the vessel’s operator, and the Titan implosion.

For approximately two weeks in September, the Coast Guard and the National Transportation Safety Board held an extensive investigation into the implosion with several witnesses and experts.

A damning portrait of the Washington-based company that developed and operated the 10.4-ton submersible as well as its founder – who charged passengers about US$250,000 ($397,700) per dive – emerged from testimony at the Coast Guard hearings.

The submersible lost contact with its mother ship on the morning of June 18, 2023. When it failed to resurface, a dramatic international search and rescue mission unfolded in the remote waters several hundred miles southeast of Newfoundland.

Authorities concluded the vessel had suffered a “catastrophic implosion,” a sudden inward collapse caused by immense pressure.

Near the debris on the sea floor, “presumed human remains” believed to belong to the victims were recovered. The remains were later matched to the five men on board through DNA testing and analysis, according to the Marine Board of Investigation.