The nuclear fallout from a Russian submarine that was sunk off the coast of Norway roughly three decades ago has spiked dramatically over the past several years, and experts are scratching their heads trying to figure out why.

According to reports, the Soviet-era vessel, which currently sits at the bottom of the Barents Sea, is now emitting radiation at levels 100,000 times higher than normal, and substantially higher than what was detected 12 years ago when earlier readings were taken.

The Kosomolets, as the sub is called, was sunk back in 1989, which resulted in the deaths of 42 of the vessel's 69 crew members. It now rests almost a mile deep, where it's been degrading and presumably becoming increasingly less radioactive.

But for whatever reason, the sub is becoming more radioactive, with strange emissions occurring from one of the vessel's ventilation holes, which experts say is kicking up "mysterious" dust clouds.