Man searches for Caribbean treasure using a secret map left by NASA astronaut

His quest is being filmed as part of a series for the Discovery Channel.

Darrell Miklos, who is documenting the experience as part of a new Discovery Channel series, told ABC News that he obtained the treasure map from his longtime friend Col. Gordon Cooper, one of NASA's 7 original astronauts, piloted last and longest of the Mercury missions. Cooper logged 222 hours in space, according to NASA, becoming the first American to sleep in space

The public purpose of Cooper’s first mission was to study the effects of prolonged weightlessness on the human body, but he had another, more secret task to carry out, one that required him to take thousands of photographs of the Earth’s surface.

In one message to ground control from space, Cooper is recorded saying, "Man, all I do is take pictures, pictures, pictures. I’m up to 5,245 now.”

Specifically, he was looking for possible Soviet nuclear missile sites off the coast of the US. According to Miklos, his friend was essentially conducting a clandestine spy mission in orbit.

"I think he had a special D.O.D. mission, Department of Defense, whereby not only was he checking how long a man could survive in space," Miklos told ABC News. "But they had some sort of long-range detection equipment ... he was utilizing that to try and identify nuclear threats that may have been placed in the Caribbean."

Miklos said that while in space, Cooper spotted hundreds of unidentified objects of interest in the Caribbean waters.

Of interest to him, that is.

"They were in shallow waters and shallow reefs, so he deduced that, 'I know what that is, those are shipwrecks,'" Miklos said.

Cooper was pretty sure these weren’t nuclear sites, but he thought the dark patches of water might hold sunken treasure. So he started making a map, later cross-referencing it with research he conducted on earth.

"He made the treasure map from space," Miklos explained.

Cooper never got to explore any of the shipwrecks he believed he found before he died, but he did share his research with Miklos. Miklos is now making it his mission to follow Cooper's treasure map and see where it leads, with Discovery Channel cameras along to document the entire journey.

"Cooper's Treasure" premieres Tuesday, April 18, 2017, on the Discovery Channel.