Greifswald (German pronunciation), officially the University and Hanseatic City of Greifswald (German: Universitäts- und Hansestadt Greifswald), is a city in northeastern Germany. It is situated in the state of Mecklenburg-Vorpommern, at an equal distance of about 250 kilometres (160 mi) from Germany's two largest cities, Berlin and Hamburg, and 80 km (50 mi) from the Polish border. The town flanks the Baltic Sea, and is crossed by a small river, the Ryck. It is also located near Germany's two largest islands, Rügen and Usedom, and it is close to three of Germany's 14 national parks. It has been the capital of the newly established district of Vorpommern-Greifswald since the September 2011 district reforms. Together with Stralsund, Greifswald forms one of four high-level urban centers of Mecklenburg-Vorpommern. The city's population was listed at 55,659 in 2013, including many of the 12,500 students and 5,000 employees of the University of Greifswald. Greifswald draws international attention due to the university, its surrounding BioCon Valley, the Nord Stream gas pipeline and the Wendelstein 7-X nuclear fusion projects.