In the process of sea development, the water level fluctuations, neotectonic movements, sedimentation rates and anthropogenic factors play an important role. Water level fluctuation and vertical movements determine the rates of long-term sedimentation. The sea level rises South of 56?N, its amplitude has been increasing from 1.5 mm y-1 (at the beginning of the 20th century) to 3-4 mm y-1 (predicted for the 22nd century). The rise of land is evident in the Central and Northern Baltic (1-9 mm y-1). These factors speed up the erosion of shallowing areas, eutrophication and accumulation of sedimentary matter in local basins. The latter processes complicate the ecological situation in the river mouth areas. The chemical composition of sediments reflect the nature of ground rocks in the denudation basin and change climatic conditions. The anthro-pogenic activity takes place in the river mouth areas, lagoons and other geochemical barriers. The mentioned factors influence the rates of sedimentation (0.6-7.5 mm y-1) which reach their maximum in the shallow areas of the East Baltic (2.5-7.5 mm y-1).