It is the best known shipwreck lying on the Irish seabed, but it is only today that the owner of the Lusitania will finally begin the first extensive visual documentation of the luxury liner that sank 93 years ago.

Gregg Bemis, who bought the remains of the vessel for £1,000 from former partners in a diving business in 1968, has been granted an imaging licence by the Department of the Environment. This allows him to photograph and film the entire structure, and should allow him to produce the first high-resolution pictures of the historic vessel.

The RMS Lusitania sank off the coast of Cork in May 1915 when a German U-boat torpedoed it. An undetermined second explosion is believed to have speeded its sinking, with 1,198 passengers and crew losing their lives.

Bemis is hoping that the week-long filming project, which begins today, will prove his theory that the Lusitania was carrying explosives, and that these were the cause of the mysterious second blast.

“I want to find out where the second explosion took place and why,” he said. “I believe there were explosives on board. I can tell the whole world that, but they’re not going to believe me until we get down there and get proof.”

JWM Productions will film the project for a television series to be shown on the Discovery Channel next year.

The 80-year-old entrepreneur only won the right to explore the wreckage, located off Kinsale’s Old Head, in March 2007. The Supreme Court granted him a five-year forensic licence after it ruled that the then minister for arts and heritage had misconstrued the law when he refused Bemis’s application in 2001.

This licence allows him to explore the wreck and to touch or move whatever is necessary to gain entrance. It relates only to filming for the month of July, and Bemis is the only member of the team that can have contact with the ship. He believes there are valuables on board belonging to passengers.

“When I did my previous dive in 2004, the visibility was 25ft maximum and the ship is 750ft long. I didn’t go very far from my shot line, so there’s much I didn’t see,” the American said.

“For the time being any objects belonging to passengers will remain down there. I own the ship, so if I want to take up parts of the ship for archeological reasons, I can do that. Anything belonging to passengers or being carried on the ship goes to the receiver of wrecks, who has to find the owner.”

Bemis plans to use the data gathered this week to measure the liner’s deterioration and to form a strategy for a forensic examination of the ship. The New Mexico-based entrepreneur estimated that this will cost $5m (€3m).

He has contracted Odyssey Marine Exploration (OME), a Florida-based company, to conduct the survey. Bemis will join the crew on board the MV Odyssey Explorer, the survey vessel, as they collect photographic and video data and assess the condition of the wreck.

The Department of the Environment’s Underwater Archaeology Unit will join the team on the survey to ensure that the research is carried out in a non-invasive manner. The survey team will employ Zeus II, a remotely operated vehicle equipped with the latest high-definition video cameras and underwater lighting. The Lusitania is 300ft below sea level and Zeus can reach 8,200ft.

John Gormley, the minister for the environment, said it is hoped that the survey will lead to a greater understanding of the events leading to the sinking of “one of the most fascinating and tragic vessels in Irish and first world war terms”.

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