For two weeks, the Northern Crown submarine rescue exercise has been conducted in parts of southern Baltic sea. The first week, the First Submarine Flotilla practiced on its own, connecting the URF (submarine rescue vessel) to a Swedish submarine. After five days, the international staff from NATO Submarine Rescue System (NSRS) joined in Karlskrona harbor. NSRS is a tri-nationally owned peacetime emergency submarine rescue capability, operated by Norway, France and the United Kingdom, and is able to operate at depths down to 600 m. It was designed to deal with pressurized rescue scenarios such as that encountered in the tragic submarine accident involving the Russian submarine Kursk in year 2000. In 2009, the three nations entered into Memorandum of Understanding with Sweden to assist each other with submarine rescue when each system carries out maintenance or is not available.