Question: What major Russian city borders the body of water that contains the island of Mährens?

full_context: Document 1: British Isles: Ireland and the United Kingdom are both part of the European Union (EU). The Crown Dependencies are not a part of the EU however do participate in certain aspects that were negotiated as a part of the UK's accession to the EU. Neither the United Kingdom or Ireland are part of the Schengen area, that allow passport-free travel between EU members states. However, since the partition of Ireland, an informal free-travel area had existed across the region. In 1997, this area required formal recognition during the course of negotiations for the Amsterdam Treaty of the European Union and is now known as the Common Travel Area.
Document 2: Großer Jasmunder Bodden: The Großer Jasmunder Bodden belongs to the Northern Rügener Boddens and is a water body on the southern edge of the Baltic Sea in the German state of Mecklenburg-Vorpommern. It is a "bodden", a type of lagoon that occurs in northern Europe especially on the coast of Pomerania. It lies within the island of Rügen, is around 14 kilometres long, an average of six kilometres wide and is up to nine metres deep with an average depth of 5.3m. The Großer Jasmunder Bodden has an area of 58.6 square kilometres; if the "Breetzer Bodden", "Breeger Bodden", "Lebbiner Bodden", "Neuendorfer Wiek" and "Tetzitzer See" are included the total area of water comes to over 94 square kilometres.
Document 3: Estonia: In 2005, Estonia joined the European Union's Nordic Battle Group. It has also shown continued interest in joining the Nordic Council. Whereas in 1992 Russia accounted for 92% of Estonia's international trade, today there is extensive economic interdependence between Estonia and its Nordic neighbours: three quarters of foreign investment in Estonia originates in the Nordic countries (principally Finland and Sweden), to which Estonia sends 42% of its exports (as compared to 6.5% going to Russia, 8.8% to Latvia, and 4.7% to Lithuania). On the other hand, the Estonian political system, its flat rate of income tax, and its non-welfare-state model distinguish it from the Nordic countries and their Nordic model, and indeed from many other European countries.
Document 4: Latvia: Latvia ( or ; , ), officially the Republic of Latvia (, ), is a country in the Baltic region of Northern Europe. Since its independence, Latvia has been referred to as one of the Baltic states. It is bordered by Estonia to the north, Lithuania to the south, Russia to the east, and Belarus to the southeast, and shares a maritime border with Sweden to the west. Latvia has 1,957,200 inhabitants and a territory of . The country has a temperate seasonal climate.
Document 5: Öhe: Öhe is an island in the Baltic Sea off the ferry port of Schaprode on Rügen, itself the largest island in Germany. The island of Öhe lies opposite Schaprode on Rügen between the lagoon of Schaproder Bodden and one of its bays, the Udarser Wiek, and is about 72 hectares in area. There is an individual farmstead on the island which has periodically fallen into disrepair and belongs to a Schilling family, who are probably descended from its owners in the 13th century. In 1990 the farmhouse was restored and is once again inhabited. The highest point on the island is the 3.3 metre high Fuchsberg.
Document 6: Heuwiese: Heuwiese is an uninhabited German Baltic Sea island that lies about two kilometres south of Ummanz and west of Germany's largest island, Rügen.
Document 7: Baltic Sea: Since May 2004, with the accession of the Baltic states and Poland, the Baltic Sea has been almost entirely surrounded by countries of the European Union (EU). The only remaining non-EU shore areas are Russian: the Saint Petersburg area and the exclave of the Kaliningrad Oblast.
Document 8: Estonia: Estonia (i/ɛˈstoʊniə/; Estonian: Eesti [ˈeːsti]), officially the Republic of Estonia (Estonian: Eesti Vabariik), is a country in the Baltic region of Northern Europe. It is bordered to the north by the Gulf of Finland, to the west by the Baltic Sea, to the south by Latvia (343 km), and to the east by Lake Peipus and Russia (338.6 km). Across the Baltic Sea lies Sweden in the west and Finland in the north. The territory of Estonia consists of a mainland and 2,222 islands and islets in the Baltic Sea, covering 45,339 km2 (17,505 sq mi) of land, and is influenced by a humid continental climate.
Document 9: Kaliningrad: Kaliningrad (Russian: Калининград, IPA: (kəljɪnjɪnˈɡrat); former German name: Königsberg; Yiddish: קעניגסבערג, Kenigsberg; Russian: Кёнигсберг, tr. Kyonigsberg; Old Prussian: Twangste, Kunnegsgarbs, Knigsberg) is the administrative center of Kaliningrad Oblast, a Russian exclave between Poland and Lithuania on the Baltic Sea.
Document 10: Baltic region: The terms Baltic region, Baltic Rim countries (or simply Baltic Rim), and the Baltic Sea countries refer to slightly different combinations of countries in the general area surrounding the Baltic Sea in Northern Europe.
Document 11: Fährinsel: Fährinsel is a small Baltic Sea island off the eastern shore of the island of Hiddensee and which belongs to the Insel Hiddensee municipality. It is separated from Hiddensee by the narrow "Bäk", only 120 metres wide in places. It forms the western part of the border between the Schaproder Bodden and the Vitter Bodden. The island is 1.23 km long and up to 580 metres wide. It has an area of ca. 37 ha. Ferry services between Rügen and Hiddensee used to run via Fährinsel. It was closed in 1952 when the port at Schaprode was upgraded to handle mailboat services. Fährinsel is a nature reserve and out-of-bounds to visitors. It is a roosting place for thousands of birds and the grazing area for a herd of Gotland sheep.
Document 12: Mährens: The German Baltic Sea island of Mährens is uninhabited and lies between the islands of Rügen and Ummanz off the coast of Mecklenburg-Western Pomerania. It is only around 150 × 100 metres across and up to 3 metres above sea level.
Document 13: Liebes: The small, uninhabited island of Liebes lies in the Baltic Sea, in the lagoon of Varbelvitzer Bodden between the islands of Rügen and Ummanz. It is a good 1,000 metres long, up to 200 metres wide and its highest point lies just 1.5 metres above sea level. The name of the island could be derived from the Slavic word "Lipa" = "lime tree".
Document 14: Poland: Poland is bordered by the Baltic Sea, Lithuania, and Russia's Kaliningrad Oblast to the north, Belarus and Ukraine to the east, Slovakia and the Czech Republic to the south, and Germany to the west.
Document 15: Langlütjen: Langlütjen is the name of the two uninhabited artificial islands created in the 19th century, "Langlütjen I" and "Langlütjen II", in the north off the coast of the district Wesermarsch in Lower Saxony, Germany. The islands are administered by the town of Nordenham. Their size is 16,000 and 17,000 square metres, respectively.
ground_truth: Saint Petersburg
sub_queries: Mährens >> located on terrain feature Answer: Baltic Sea
which major russian city borders Baltic Sea Answer: Saint Petersburg