The Väinameri Sea

The Väinameri Sea ("the Sea of Straits") is a shallow sea part with an approximate area of 2200 km², where a large number of small islands and bays are located. It stretches between the islands of West Estonia (Saaremaa, Hiiumaa, Muhu, Vormsi) and the mainland. The islands and the mainland are separated by straits: Voosi Kurk, Hari Kurk, Soela, Väike Väin and Suur Väin. In 1894–1896, a 3.6 m long causeway connecting Saaremaa and Muhu was constructed across Väike Väin Strait. Across the eastern part of the Väinameri Sea, earlier known as Moonsund, an important and complicated waterway leads from the Gulf of Finland to the Gulf of Riga. Paternoster — the mediaeval name of Viirelaid Islet located close to the mouth of the Suur Väin Strait — refers to the dangerousness of this waterway.

Shipping lanes leading across the straits were dredged before World War I when a navel port was established in Rohuküla. These were the most extensive works of that kind ever carried out by tsarist Russia. The Väinameri Sea is too shallow for big ships; its mean depth is 5 m, and only the Suur Väin Strait is up to 24 m deep. There is a ferry connection between the larger islands of the Väinameri Sea, as well as between these islands and the mainland. The complicated navigation conditions and the variety of landscapes have made the Väinameri Sea popular among yachtsmen. The main commercial fish in the Väinameri Sea is Baltic herring; perch and garpike are also of some importance.

Islands of the Väinameri Sea
From anywhere in the Väinameri Sea, either the coastline or small islands can be seen. Of 1500 Estonian sea islands (i.e. islands with an area exceeding 900 m²), 600 are situated here. In addition to the above-mentioned main islands, there are only 10 more islands the area of which exceeds 1 km²; most islands are actually smaller than 0.1 km². As a result of surface uplift, new islands emerge gradually from the sea and the area and height of the existing ones is continuously increasing. Thus, the islands are very different: they range from bare land lots covered with gravel and shingle to islands covered with lush vegetation. There are several words in Estonian for ‘island’ — laid, rahu, kare, kuiv, nasv — depending on the size, age and look of the islands. Diversity of the existing habitats — shallow bays grown over with reed, islands offering protection against predators (as well as against people) — has created favourable conditions for a species-rich flora and fauna, and especially for birds. In the region of the Väinameri Sea, several protected areas have been established: Matsalu Nature Reserve (total area 486.1 km², of which sea area 236 km²) which is one of the most important bird protection areas in Europe; Käina Bay – Kassari Nature Reserve (35.5 km²); and Hiiumaa Islets Landscape Reserve (26.6 km²). Nearly all of the area is included in West-Estonian Archipelago Biosphere Reserve.

Hydrology of the Väinameri Sea
The hydrological conditions of the shallow and small Väinameri Sea differ considerably from the hydrological conditions of the parts of open sea to the west of the islands. In the Väinameri Sea waves are lower, annual fluctuations of water temperatures bigger and the water salinity lower. Also, water in the Väinameri Sea is less transparent and ice cover here is thicker and remains for a longer period of time than on the open sea areas.

In summer, water is the warmest in the bays of the western coast of Estonia, Haapsalu and Matsalu bays, where the mean water temperature in July is 19°–20°C and, in exceptionally warm days, even 25°–28°C. Already 150 years ago, Dr. K. A. Hunnius, a doctor in Haapsalu seaside resort, found the water in the above-mentioned bays as warm as in the Mediterranean seaside resorts. A seaside resort in Haapsalu was however primarily established thanks to the large supplies of curative mud on the bottom of Haapsalu Bay.

However, these bays have also the most severe ice conditions in Estonia. Although winters may be very different, the Väinameri Sea freezes every winter. This period usually lasts for 4 months and in very mild winters only for 2 months. In severe winters, a road across the ice between islands and the mainland is opened for car traffic.

Details about this article