St. PETRESBURG, June 30. /TASS/. Archaeologists from the St. Petersburg-based Institute of Material Culture have set off on an expedition to explore and map out the ancient underwater city of Akra known as the Crimean Atlantis.

"Our task is to produce the city’s topographic plan. We have some landmarks near the coastline but the rest is terra incognita," Sergei Solovyov, the expedition’s head, told TASS on Friday.

"We brought along new sonars to work with in deep waters," he added.

Akra, once a prosperous city in eastern Crimea, belonged to the Bosporus Kingdom and submerged some 2,000 years ago.

The archaeologists examined two walls and a tower during their previous expeditions and also found the remains of residential buildings.