Abstract: Seabed characteristics applied for classification was based on analysis of echo recordings collected aboard RV "Baltica" during regular surveys in 1995-2003 period. Hypothetical effective angle of a bottom echo θ’/2, corresponding to its normalized length was applied to characterize complex seabed acoustic reflecting and scattering properties. The θ’/2 values were determined for each EDSU. Classification of southern Baltic area was provided by comparison of two acoustically measured factors: statistical distribution of θ’/2 and correlated depth structure within selected standard areas. Both factors are very closely related to biological characteristics of the benthic habitat. Joining them gives a wide possibility of differentiating the habitat by its basic ecological properties. The classification applied gave a unique identification and comparison of dynamics of seabed structures, useful for benthic surveys and helpful in ecologically friendly administration of the zone.