Kiel is the capital and most populous city in the northern German state of Schleswig-Holstein. With a population of around 250,000, it is Germa…Kiel is the capital and most populous city in the northern German state of Schleswig-Holstein. With a population of around 250,000, it is Germany's largest city on the Baltic Sea. It is located on the Kieler Förde inlet of the Bay of Kiel, and lies in the southeast of the Jutland Peninsula, on the mouth of the Schwentine River, approximately 90 kilometres northeast of Hamburg. In Kiel-Holtenau begins the world's busiest artificial waterway, the Kiel Canal, that connects the Baltic to the North Sea. Most of Kiel is part of Holstein. The boroughs north of the Schwentine also belong to Wagria, while those north of the Kiel Canal are historically part of Southern Schleswig.