The IJsselmeer, also known as Lake IJssel in English, is a closed-off inland bay in the central Netherlands bordering the provinces of Flevoland, North Holland and Friesland. It covers an area of 1,100 km2 (420 sq mi) with an average depth of 4.5 m (15 ft). The river IJssel, which is what the lake was named after flows into the IJsselmeer.

Flevoland is the twelfth and newest province of the Netherlands, established in 1986, when the southern and eastern Flevopolders, together with the Noordoostpolder, were merged into one provincial entity. It is in the centre of the country in the former Zuiderzee, which was turned into the freshwater IJsselmeer by the closure of the Afsluitdijk in 1932. Almost all of the land belonging to Flevoland was reclaimed in the 1950s and 1960s while splitting the Markermeer and Bordering lakes from the IJsselmeer. As to dry land, it is the smallest province of the Netherlands at 1,410 km2 (540 sq mi), but not gross land as that includes much of the waters of the fresh water lakes (meres) mentioned.