A hoard of silver coins worth £34million that was sunk by the Nazis on board a steamship has been salvaged by a British-led team at a record depth of 5,150m ( 17,000ft ) . The SS City of Cairo was travelling from Bombay to England in 1942 when it was torpedoed by a U-boat 480 miles south of St Helena , taking 100 tons of rupees with it to the bottom of the ocean . It was long assumed that the vessel 's cargo , belonging to the UK Treasury , would be lost forever such was the complexity of the task facing salvage experts . Treasure trove : Some of the 100 tons of rupees found buried in the ocean floor at a record depth of 17,000ft after the cargo ship they were being transported on was sunk by a Nazi submarine during World War Two . Record find : Some coins are raised to the surface during a pioneering recovery project by a British-led team . Hidden : The City of Cairo was finally discovered ( above ) 'broken in two and buried deep in the seafloor silt ' Underwater company Deep Ocean Search used powerful sonar to locate the vessel on the sea floor . That was until a team led by British expert John Kingsford used pioneering techniques to track down the ship with powerful sonar and robotics . Underwater company Deep Ocean Search ( DOS ) , which included 20 French oceanographers , was then contracted by the UK Ministry of Transport to recover the coins from a record depth of 17,000ft - some 4,500ft deeper than the Titanic . A spokesman for DOS said : 'This was to be a difficult search as the water depth would exceed 5,000m , the weather , swell and currents were known to be challenging and the presumed site was some 1,000 miles from the nearest land in the foothills of the mid-Atlantic ridge . ' When the ship was finally discovered , it was 'broken in two and buried deep in the seafloor silt ' , adding that 'parts of the ship had metres of mud heaped upon it . ' The SS City of Cairo was sunk en route from Bombay to India , via Cape Town and Recife in Brazil . The rupees , belonging to the UK Treasury , were being transported from India to England when the ship sunk . Underwater company Deep Ocean Search , which included 20 French oceanographers , was contracted by the UK Ministry of Transport to recover the coins from a record depth of 17,000ft - 4,500ft deeper than the Titanic . Keeping it under wraps : The recovery took place in 2013 , but has only now been made public . The SS City of Cairo was travelling from Bombay to England , via Cape Town and Recife , Brazil , when it was attacked by a Nazi U-Boat on November 6 , 1942 . The U-68 hit the vessel with one torpedo , but waited a further 20 minutes before firing the second . That crucial delay gave 296 of the ship 's 302 passengers and crew time to escape in lifeboats . Famously , the German captain , Karl-Friedrich Merten , approached the lifeboats and told the survivors : 'Goodnight , sorry for sinking you . ' The victims were eventually rescued three weeks later , but 104 had died . Maeva Onda , one of the oceanographers on board the salvage ship , SV John Lethbridge , said the search submarine was successful on its first dive . 'After two hours of underwater descent , the robot transmitted the first images of the wreck . It was incredible , ' she told Le Figaro , as cited by the Daily Telegraph . The find was confirmed when the robot brought up coins stamped with the Crown . But the team suffered 'serious ' problems trying to recover the bulk of the hoard because of the depths involved . The spokesman for DOS said : 'The team quickly found that operating at this depth caused serious technical difficulties which were new to us and which had to be resolved , quickly . 'The combination of pressure , temperature , repeated dives at this depth and other issues resulted in multiple breakdowns of systems such as we had not experienced before when working in 3000m to 4000m depths . ' The recovery took place in 2013 , but has only now been made public . DOS has left a plaque commemorating their find on the sea bed . Maeva Onda , one of the oceanographers on board the salvage ship , SV John Lethbridge , said the search submarine was successful on its first dive , adding : 'It was incredible '
SS City of Cairo sunk by U-boat en route from Bombay to England in 1942 . 100 tons of rupees belonging to 104 thought to be lost forever . Finally tracked down by British-led team using powerful sonar and robotics . Recovered from a depth of 17,000ft – some 4,500ft deeper than the Titanic .