MT Unirea was a Romanian-flagged crude oil carrier, one of the biggest ships of the Romanian commercial fleet. She broke up and sank in 1982 in the Bulgarian waters of the Black Sea, 40 nautical miles 74 km south-south east of the Cape Kaliakra at a depth of 1,400 metres 4,600 ft after a mysterious explosion.The crew totalled 43 members of which 42 were rescued by Romanian and Soviet boats. The sinking of Unirea was classified by Lloyd's List as the largest ship accident of 1982.The exact cause of accident is unknown but official reports suggest that during a vapor evacuation of the central number 3 tank an explosive mixture formed alongside the evacuation hole that could have been ignited by multiple sources but especially electrostatic energy. The explosion of the central number 3 tank had a devastating effect on the integrity of the ship triggering a series of explosions that destroyed the separating wall of the central and starbord tanks favoring the expansion of the volatileelements across the ship.