It's a mystery dating back almost a hundred years, a state of the art submarine — lost. But why? Well researchers finally have the answer.

Its name was Akula which stood for "The Shark." Launched in 1911, it was at the time, a revolutionary vessel. With a crew of 35, this 400 ton ship was believed to be one of Russia’s first battle submarines.

However, in 1915, at the height of the first world war, The Shark simply disappeared somewhere in the Baltic Sea.

Fast forward one hundred years and a team of divers from Estonia believe they have solved the mystery. 40 yards below the Baltic surface they found a suspicious wreck.

Although they weren’t able to swim inside the wreck due to the damage, they were able to make out the name Akula on the hull. A hull that had been blasted away from the rest of sub, presumably from a German mine, which during the war littered the Baltic Sea.

The divers who found the wreck are now hoping the Russian ministry will declare the sub a "brother’s grave," honoring the final resting place for the men who died inside.

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