A group of divers have explored the wreckage of a First World War-era Royal Navy submarine 100 years after it sank.

Professional shipwreck diver and YouTuber Dominic Robinson and a team of 10 dived down to check out the century-old M1 sub 20 miles off the coast of Plymouth in mid-August.

They found her in a wreck, missing the famed 12-inch gun—typical of the era’s battleships—which she apparently carried as armament.

The HMS M1 was constructed during WW1 but was never used in combat due to fears the Germans would copy its revolutionary design.

The sub sank in 1925 when a Swedish ship, the SS Vidar, is believed to have accidentally struck her while she was submerged—leading to the loss of all crew—another little tragedy amid the tragic, inconclusive European conflict.

It was missing until a salvage team located it in 1967 and was then formally identified by a dive team in 1999.

Described by Robinson in a film made of the dive as “one of the most incredible submarines ever built.”

“We were on the water for about three hours so it’s a fairly significant effort for about 25 minutes of diving to look around the wreck,” Robinson told England’s Southwest News Service. “The general view is the collision knocked the gun off the mount, and I think the weight of it has carried it into the sand beneath the main wreckage.”

Robinson claims that diving like this is rare and “well beyond” what many divers will do.

“If you were to go Egypt or somewhere like that they would take you to 20 meters, advanced would be 30 meters, and if you really pushed it 40 meters. This is 74 meters. so it’s well beyond what 99% of divers will do, but we want to see things that people don’t see.”

Robinson’s YouTube channel—Deep Wreck Diver—has 13,500 subscribers and is dedicated to showing viewers deep shipwrecks.

“I want to help people understand and the history of these things that are forgotten,” he said.

WATCH a 40-minute film of the dive….

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