Кваркен: География, история и перспективы пролива в Ботническом заливе.

Region of the Gulf of Bothnia separating the Bothnian Bay from the Bothnian Sea
Several attempts to cross the strait swimming have been made, but cold water and currents have usually been insurmountable obstacles. The first successful crossing was carried out by Lennart Flygare, Pavio Grzelewski and Tore Klingberg, who on 24 July, 2018, swam from Valassaaret (Valsörarna) on the Finnish side to Holmöarna in Sweden. It took them 12 hours 2 minutes to cross the strait.

On the Finnish side of Kvarken, there is a large archipelago, the Kvarken Archipelago, which includes the large islands Replot, Björkö and over 5,600 smaller islands. Most of it belongs to the municipality of Korsholm. Most of the small islands are inhabited. The archipelago is smaller on the Swedish side of the region, and the islands, part of Umeå Municipality, have much steeper shores. The Kvarken region was historically important also, because mail was delivered across Kvarken when the sea was completely frozen from the Swedish to the Finnish coast. This mail route was used frequently during the period when Finland was a part of Sweden. During the Ice Ages, the Kvarken region was located underneath the Fennoscandian ice sheet. In 2006, parts of the Kvarken Archipelago were added as an extension to the World Heritage Site of the High Coast (located on the western shore of the Gulf of Bothnia) in Sweden, because of its outstanding demonstration of isostatic uplift, and the influence of glacial retreat on the evolution of landforms and topography. The most Finnish parts of the High Coast/Kvarken Archipelago World Heritage Site are situated in the Korsholm municipality. In the group of islands in the “middle” of the Kvarken region, in Swedish called Valsörarna – Finnish Valassaaret, is a lighthouse designed by fr who worked for Gustave Eiffel's engineering bureau. The structural similarity between the lighthouse (built in 1885) and the Eiffel Tower (built in 1889) is quite obvious. The lighthouse is now automated as are most lighthouses in Finland.

There have been proposals for a bridge across the strait, at a cost of about 1.5 to 2 billion euros. There are islands in the strait, and the sum of the lengths of the probably three bridge parts would be about The Swedish minister of finance has said it is an interesting idea, but the idea is still decades from being brought to fruition. There is a debate in the coastal cities on both sides, like Umeå and Vaasa. The official view from the Swedish and Finnish governments is that it is much too expensive, also put in regard that the cities are very small by European standards, as compared to Copenhagen and Malmö between the Oresund fixed link. The natural values of the area also make a bridge dubious.