The Bothnian Sea links the Bothnian Bay

Bothnian Bay

The Bothnian Bay or Bay of Bothnia is the most northern part of the Gulf of Bothnia, the northern part of the Baltic Sea. Its northernmost point is situated in Töre...

 (called also Bay of Bothnia) with the Baltic proper

Baltic Sea

The Baltic Sea is a brackish mediterranean sea located in Northern Europe, from 53°N to 66°N latitude and from 20°E to 26°E longitude. It is bounded by the Scandinavian Peninsula, the mainland of Europe, and the Danish islands. It drains into the Kattegat by way of the Øresund, the Great Belt and...

. Kvarken

Kvarken

Kvarken is the narrow region in the Gulf of Bothnia separating the Bothnian Bay from the Bothnian Sea...

 is situated between the two. Together, the Bothnian Sea and Bay make up a larger geographical entity, the Gulf of Bothnia

Gulf of Bothnia

The Gulf of Bothnia is the northernmost arm of the Baltic Sea. It is situated between Finland's west coast and Sweden's east coast. In the south of the gulf lie the Åland Islands, between the Sea of Åland and the Archipelago Sea.-Name:...

. The whole Gulf of Bothnia is situated between Sweden

Sweden

Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

, to the West, Finland

Finland

Finland , officially the Republic of Finland, is a Nordic country situated in the Fennoscandian region of Northern Europe. It is bordered by Sweden in the west, Norway in the north and Russia in the east, while Estonia lies to its south across the Gulf of Finland.Around 5.4 million people reside...

, to the East, and the Sea of Åland

Sea of Åland

The Sea of Åland is the waters located in the southern Gulf of Bothnia, between the Åland islands and the Swedish mainland. The sea connects Kvarken and the Bothnian Sea with the Baltic Sea proper. The seas are often choppy here. The narrowest part is named Södra Kvarken or South Kvarken....

 and Archipelago Sea

Archipelago Sea

Archipelago Sea is a part of the Baltic Sea between the Gulf of Bothnia, the Gulf of Finland and the Sea of Åland, within Finnish territorial waters...

 to the South.
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The surface area of Bothnian Sea is approximately 79,000 km². The largest coastal towns, from south to north, are Rauma

Rauma, Finland

Rauma is a town and municipality of ca. inhabitants on the west coast of Finland, north of Turku, and south of Pori. Granted town privileges on May 17, 1442 , Rauma is known of its high quality lace , and of the old wooden architecture of its centre , which is a Unesco world heritage...

 and Pori

Pori

Pori is a city and municipality on the west coast of Finland. The city is located some from the Gulf of Bothnia, on the estuary of the Kokemäenjoki river, which is the largest in Finland. Pori is the most important town in the Satakunta region....

 in Finland, and Gävle

Gävle

Gävle is a city in Sweden, the seat of Gävle Municipality and the capital of Gävleborg County. It had 71,033 inhabitants in 12/31 2010. It is the oldest city in the historical Norrland , having received its charter in 1446 from Christopher of Bavaria.-History:It is believed that the name Gävle...

 and Sundsvall

Sundsvall

-External links:* - Official site from Nordisk Familjebok - Sundsvalls tourist information bureau. - The alternative guide to Sundsvall. - Blog with photos from Sundsvall....

 in Sweden. Umeå

Umeå

- Transport :The road infrastructure in Umeå is well-developed, with two European highways passing through the city. About 4 km from the city centre is the Umeå City Airport...

 (Sweden) and Vaasa

Vaasa

Vaasa is a city on the west coast of Finland. It received its charter in 1606, during the reign of Charles IX of Sweden and is named after the Royal House of Vasa...

(Finland) lie in the extreme north, near Bothnian Bay.