Of a world in coronavirus turmoil, they may know little or nothing.

Submariners stealthily cruising the ocean deeps, purposefully shielded from worldly worries to encourage undivided focus on their top-secret missions of nuclear deterrence, may be among the last pockets of people anywhere who are still blissfully unaware of how the pandemic is turning life upside down.

Mariners aboard ballistic submarines are habitually spared bad news while underwater to avoid undermining their morale, say current and former officers who served aboard France’s nuclear-armed subs.

So any crews that left port before the virus spread around the globe are likely being kept in the dark about the extent of the rapidly unfurling crisis by their commanders until their return, they say.

“They won’t know,” said retired Admiral Dominique Salles, who commanded the French ballistic submarine squadron from 2003-2006. “The boys need to be completely available for their mission.”

Speaking exclusively to The Associated Press, Salles said he believes submariners will likely only be told of the pandemic as they head back to port, in the final two days of their mission. “Those who are at sea don’t need this information,” said Salles.

“The commander, I think, is doubtless informed about what is happening. I don’t think he’ll have all the details,” he said. The French navy won’t divulge what has or hasn’t been said to submarine crews. Nor will it say whether any of the four French ballistic submarines, left harbour before France instituted a nationwide lockdown on March 17.