Gulf of Riga

The Gulf of Riga is a semi-enclosed arm of the Baltic Sea bounded by Latvia to the east and south and Estonia to the north. Mean astronomical tidal range is 2–5 cm — effectively zero. Water level is governed by wind-driven seiches, storm surges, and atmospheric pressure gradients. A sustained westerly can raise the eastern shore of the Gulf by 0.5–1.0 m; a high-pressure system pressing down on the Baltic can suppress levels 0.3–0.5 m below the long-term mean. Riga sits at the Daugava River mouth where freshwater discharge interacts with Gulf salinity; Jūrmala is the resort strip on the narrow sand peninsula that separates the Lielupe River from the Gulf; Ventspils, on the open Baltic coast to the northwest, is Latvia's most important ice-free port.