Bay of Bothnia
| Bothnian Bay | |
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The rocky shoreline of Ohtakari, in the southeast of the bay
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 Bothnian Bay
Location in Europe
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| Location | Fennoscandia |
| Coordinates | 65°N 023°E / 65°N 23°ECoordinates: 65°N 023°E / 65°N 23°E |
| Type | Sea |
| Primary outflows | Bothnian Sea |
| Catchment area | 260,675 km2 (100,647 sq mi) |
| Basin countries | Finland, Sweden, Norway |
| Surface area | 36,800 km2 (14,200 sq mi) |
| Average depth | 43 m (141 ft) |
| Max. depth | 147 m (482 ft) |
| Water volume | 1,490 km3 (360 cu mi) |
| Frozen | 110–190 days annually |
The Bothnian Bay or Bay of Bothnia (Swedish: Bottenviken, Finnish: Perämeri) is the northernmost part of the Gulf of Bothnia, which is in turn the northern part of the Baltic Sea. The land holding the bay is still rising after the weight of ice-age glaciers has been removed, and within 2,000 years the bay will be a large freshwater lake. The bay today is fed by several large rivers, and is relatively unaffected by tides, so has low salinity. It freezes each year for up to six months. Compared to other parts of the Baltic it has little plant or animal life.
The bay is divided from the Bothnian Sea, the southern part of the Gulf of Bothnia, by the Northern Quark (Kvarken) strait. The Northern Quark has a greatest depth of 65 metres (213 ft), with two ridges that are just 25 metres (82 ft) deep. It lies between a group of islands off Vaasa in Finland and another group at Holmöarna in Sweden. The bay is bounded by Finland to the east and Sweden to the west. The bay is asymmetric, with a smoother and shallower bottom slope on the Finnish side, and a deeper bottom with a steeper and more rugged coast on the Swedish side.
The Bothnian Bay has a catchment area of 260,675 square kilometres (100,647 sq mi). Of this, 56% lies in Finland, 44% in Sweden and less than 1% in Norway. The catchment contains about 11,500,000 hectares (28,000,000 acres) of forest, split roughly equally between Sweden and Finland.
The average depth is 41 metres (135 ft). The Luleå Deep is the deepest part of the bay, at 146 metres (479 ft), southeast of the town of Luleå. On the Finnish side the average depth is 30 metres (98 ft). The deepest part is near the island of Lönkytin, with a depth of 50 metres (160 ft).
Map of the Gulf of Bothnia showing location of Bothnian Bay (shaded and labelled Bottenviken)
Finnish map of the bay – click to enlarge
Satellite image of Fennoscandia with sea ice covering the Bothnian Bay (white region in center)
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Wikipedia