The U234 which delivered the Uranium Oxide U235 to Doctor Oppenheimer of the US Manhattan project at Porstmouth about May 13, 1945. The Uboat officers/ crew said they cruised at 900 feet/175m or deeper to keep away from our depth charges. It was commonly know by the UBoat arm that many types of UBoats could cruise at 300m/985'. The US and Allied Navies did not believe any submarine could go below 300' so set their depth charges above that level.