«The lakes were agitated, the copper mountains trembled... »

Data from hydrographic and paleoseismological studies of Northwest Russia can shed light on a number of historical events described in Russian chronicle sources, as well as in the poetic images of the Kalevala. The reasons for the regression (retreat) of the Baltic Sea and significant changes in the coastline of the Baltic-Ladoga water system may be associated with a series of seismic disasters in the 12th-13th centuries.