According to Greece's Culture Ministry, the third-century wreckage were found nearly a mile deep between Corfu and Italy, which suggests that ancient seafarers didn't "hug the shore" were more adventurous than thought.
The wreaks lay between 0.7-0.9 miles deep in the sea which would place them among the deepest known ancient wrecks in the Mediterranean, apart from remains found in 1999 of an older vessel some three kilometres deep off Cyprus.
Angeliki Simossi, head of Greece's underwater antiquities department, said sunken ancient ships are generally found 100-130 feet deep.
Most scholars believe that ancient traders were unwilling to veer far offshore, unlike warships which were unburdened by ballast and cargo.
"There are many Roman shipwrecks, but these are in deep waters. They were not sailing close to the coast," Simossi was quoted as saying by the Daily Mail.
"The conventional theory was that, as these were small vessels up to 80 feet long, they did not have the capacity to navigate far from the coast, so that if there was a wreck they would be close enough to the coast to save the crew."
US archaeologist Brendan Foley, who was not involved in the project, said a series of ancient wrecks located far from land over the past 15 years has forced experts to reconsider the coast-hugging theory.
"The Ministry of Culture's latest discoveries are crucial hard data showing the actual patterns of ancient seafaring and commerce," said Foley, a deep water archaeology expert at the Woods Hole Oceanographic Institution in Massachusetts.
The wrecks were found earlier this month during a survey of an area where a Greek-Italian gas pipeline is to be sunk.