It entailed building a ship for the mission, the Hughes Glomar Explorer, with the cover that it was part of the billionaire’s deep sea mining research for manganese nodules.

The agency decided it would refuse to confirm or deny whether records about the Glomar Explorer’s mission existed, despite the mounting public evidence that they did. And so the “Glomar response” was ...

FILE - This March 19, 1975 file photo shows the Hughes Glomar Explorer, a 618-foot-long salvage ship built by the eccentric industrialist Howard Hughes, at the Long Beach harbor dock in Los ...

1975 photo of Hughes’ Glomar Explorer, used in a CIA effort to retrieve a sunken Russian sub. The top-secret ship was anchored in Suisun Bay’s ‘mothball fleet’ for years. By Brendan Riley ...

With an elaborate cover story and the help of billionaire Howard Hughes, the CIA spent the current value of $1.3 billion to build an ambitious deep-sea platform, Hughes Glomar Explorer, which ...

The Hughes Glomar Explorer, a 618-foot-long salvage ship built by Howard Hughes, sits at the Long Beach harbor dock in Los Angeles, March 19, 1975. The crane barge that's been hauling away ...

The Glomar Explorer has since been renamed and used for deep-sea oil drilling and exploration, according to the intelligence agency. Like the ship, the Sun 800 also found new purpose.