Shipwrecks in Estonian waters which contain fuel, ammunition or 'ghost nets' and could cause environmental damage have been accessed and mapped by the National Heritage Board (Muinsuskaitseamet).
At the request of the National Heritage Board (Muinsuskaitseamet), three diving companies and navy investigated 12 ships which sank in the 20th century.
One of the wrecks is the German submarine U479 which crashed into a mine during World War II and is lying on the sea bed 90 meters below the surface.
Maili Roio, senior inspector of the Underwater Heritage Office said: "No major damage has occurred. The mine explosion has not caused a fuel leak. There are also no other explosives around."
The second wreck is the Russian submarine Akula, which lost its bow in World War I. The wreck is 30 lying 30 meters below the surface and is surrounded by mines.
In addition to the Maritime Administration and the diving companies, the Estonian Navy also participated when investigating the wrecks.
Lieutenant-Commander Mati Terve said: "The Navy's role in this was to evaluate the five shipwrecks in the light of the environmental hazards it poses, what ammunition it is on, and how or not to blast them."
However, ammunition and diesel are not the only sources of danger with such wrecks. Roio said 'ghost nets' are dangerous because they can get caught in trawler ships' nets.
At 60 meters deep, the Soviet submarine M 103 is completely covered with trawl nets where fish and seals are caught in the video. These nets should be removed, said Maili Roio.
Pumping out fuel from the wrecks in the event of a spill is the next challenge. "There are technologies to retrieve fuel. There is also fuel freeing. But it's a pretty expensive venture," Roio said.
The documentation of the 12 wrecks cost €230,000. In the 20th century, about 500 ships sank in Estonian waters.
Editor: Helen Wright