In 1968 a B-52 bomber carrying 4 H-bombs caught fire and crashed near Thule, Greenland, scattering plutonium over a wide area. One of the Bombs melted through the ice and sank to the floor of the Arctic Ocean. Two years earlier a similar incident occurred in Palomares Spain, but in that case the Bomb that went to the bottom was retrieved by means of a massive rescue operation involving over 30 ships.