The Hughes “Glomar Explorer”Golf-II Class submarine, sank in the Pacific on April 11th, 1968 with a full complement of nuclear ballistic missiles on board. The CIA concocted a plan to enlist the billionaire Howard Hughes to build a ship that would be capable of lifting the sub off the ocean floor 17,000 ft. below.
It had long been known the ocean floor was littered with chunks of magnesium mixed with other useful metals. Hughes made it known that he was going to build a ship The Hughes Glomar Explorer for the purpose of harvesting these metals. Other mining companies were so taken in that they began their own deep-sea mining operations. In fact, the entire enterprise was a cover for the CIA.
In June of 1974, the completed Glomar Explore attempted to lift the ship. It was partially successful, as the sub broke apart during the operation. Only part of the sub was ultimately recovered - including the bodies of 8 Soviet sailors who were filmed being buried at sea in a bizarre ceremony. What materials were actually recovered are still classified. More details can be found here.
One wonders who the CIA could even turn to these days to pull off that sort of an undertaking. The bottom line is: they just don’t make billionaires like they used to; do pompous blowhards like Larry Ellison, CEO of Oracle, or geeky shut-ins like Steve Case of AOL and Michael Dell of Dell Computer even hold a candle to Howard Hughes?