Danton wreck found in deep water

By Jonathan Amos Science reporter, BBC News

The Danton was carrying over 1,000 men at the time

A French battleship sunk in 1917 by a German submarine has been discovered in remarkable condition on the floor of the Mediterranean Sea.

The Danton, with many of its gun turrets still intact, is sitting upright in over 1,000m of water.

It was found by the Fugro geosciences company during a survey for a gas pipeline between Algeria and Italy.

The ship, which sank with 296 sailors still onboard, lies 35km southwest of the island of Corsica.

"Its condition is extraordinary," said Rob Hawkins, project director with Fugro GeoConsulting Limited.

"After it was hit by the torpedoes, the Danton clearly turned turtle and rotated several times. You can see where it dropped some infrastructure on the way down and then impacted on the seabed.

"You can see where it slid along the seabed before coming to a rest," he told BBC News.

The wreck is just off the point where the southern pipeline meets Sardina

A comparison with the original plans for the battleship confirms the wreck's identity. The position is a few kilometres from where people have traditionally thought the ship met its end.

"The French Admiralty did argue with us for a while that it should have been several nautical miles away, but we reminded them that modern GPS methods are more accurate than the sextants they used in those days," said Mr Hawkins.

Details of the discovery were released on Thursday at a press conference at the Museum of Science and Technology in Milan.

The pipeline is being built by the Galsi (Gasdotto Algeria Sardegna Italia) consortium and will be the deepest underwater conduit for gas ever constructed when it becomes operational in 2012.

Finding a safe route for it was extremely challenging, said Mr Hawkins.

About 20% of the course lies on the abyssal plain in water depths of about 2,850m. There are also steep descents from the continental shelf.

Fugro can deploy an array of geophysical survey equipment

Fugro deployed its Autonomous Underwater Vehicle to gather bathymetric and geophysical data.

It also used Remotely Operated Vehicles to make more detailed surveys of particular locations, such as where sediment conditions were uncertain or the route crossed known submarine telecommunications cables.

The discovery of the Danton, named after the French revolutionary Georges Danton, requires the gas feed must take a slight detour to avoid the war grave.

The ship was one of the most advanced in the French Navy at the time of its loss, although it was already outclassed by the newer HMS Dreadnought design being introduced by the British.

The 19,000-tonne, 150m-long vessel was carrying over 1,000 men when it was attacked by Germany's U-64 submarine. Patrol boats and a destroyer managed to save most of those onboard.

Jonathan.Amos-INTERNET@bbc.co.uk