Constance, Germany - Archaeologists believe Lake Constance is a huge ships' graveyard for historical vessels dating back to ancient times.
Martin Mainberger of the regional office for the preservation of historical monuments said Tuesday 50 shipwrecks have already been identified in Lake Ueberling, a northern arm of Lake Constance.
Underwater archaeologists from Europe and the United States are currently meeting at Constance in southern Germany as part of an international conference on underwater archaeology in Zurich.
The experts are unsure how many ships may be lying on the bed of Lake Constance which borders Germany, Switzerland and Austria.
Researchers only began to realise just what historical treasures were hidden in the lake when a 14th-century load sailboat was discovered in 1992 at the northern bank near Immenstaad.
"It is only a question of time before an antique ship from Roman times is found," said archaeologist Helmut Schlichtherle. Even dug-out canoes dating back more than 2 000 years could be on the bed, he said. - Sapa-dpa