Bay in the eastern part of the Baltic Sea washes the shores of Finland, Russia and Estonia. West Bay is considered to be an imaginary boundary line between Hanko peninsula and Cape Pyyzaspea . The area of ​​the Gulf of 29.5 thousand sq. Km , length 420 km, the width of the throat 70 km up to 130 km at its widest point , the average depth of 38 m (maximum 121 m) .