The vessel was discovered by fishermen trailing nets along the sea bottom some 15 miles off the coast, said Dimitar Nedkov, head of the Archaeological Museum in the port city of Sozopol.
"The dugout is 2.6 meters (8.5 feet) long and 70 centimeters (27.5 inches) wide, and it is made most probably of oak," Nedkov told The Associated Press.
Bulgarian explorers have found four ancient vessels in remarkably good condition in the Black Sea, whose oxygen-depleted deep water preserves wrecks without the worm damage and deterioration that normally affects wooden vessels.
"Nowhere else can you find similar dugouts, as well as any kind of wooden vessels over 300 years old, because water rots the wood away," said Bozhidar Dimitrov, head of the National Museum of History. "In the Black Sea, however, there is dissolved hydrogen sulfide below a certain depth which preserves all organic materials."