What event in 1170 may have caused the creation of 5,000 km2 large shallow bay of the North Sea in the northwest of the Netherlands?
Zuiderzee The Zuiderzee (] ; old spelling "Zuyderzee") was a shallow bay of the North Sea in the northwest of the Netherlands, extending about 100 km (60 miles) inland and at most 50 km (30 miles) wide, with an overall depth of about 4 to 5 metres (13–16 feet) and a coastline of about 300 km (200 miles). It covered 5,000 km2 . Its name means "southern sea" in Dutch, indicating that the name originates in Friesland, to the north of the Zuiderzee (cf. North Sea). In the 20th century the majority of the Zuiderzee was closed off from the North Sea by the construction of the Afsluitdijk, leaving the mouth of the inlet to become part of the Wadden Sea. The salt water inlet changed into a fresh water lake now called the IJsselmeer (IJssel Lake) after the river that drains into it, and by means of drainage and polders, an area of some 1500 km2 was reclaimed as land. This land eventually became the province of Flevoland, with a population of nearly 400,000 (2011).
Maritime history of England The Maritime history of England involves events including shipping, ports, navigation, and seamen, as well as marine sciences, exploration, trade, and maritime themes in the arts of England. Until the advent of air transport and the creation of the Channel Tunnel, marine transport was the only way of reaching the rest of Europe from England and for this reason, maritime trade and naval power have always had great importance. Prior to the Acts of Union in 1707, the maritime history of the British Isles was largely dominated by England.