Copenhagen, the capital of Denmark, with a population between 1.3 and 1.4 million people in 2020, is located mostly on the eastern shore of Zealand and partly on the island of Amager.

Other cities on Zealand include Roskilde, Hillerød, Næstved, Helsingør, Slagelse, Køge, Holbæk and Kalundborg.

However, today a common hypothesis is that the Old Danish form Siâland is based on the word *selha- with the ending *wundia-.

The word *selha- may have two different meanings: "seal" (in modern Danish sæl) or "deep bay, fjord".

The Jutes migrated to Great Britain eventually, some as mercenaries of Brythonic King Vortigern, and were granted the south-eastern territories of Kent, the Isle of Wight and other areas, where they settled.

With its strategic location at the entrance to the Øresund, especially after the construction of Kronborg Castle and the introduction of Sound Dues, Helsingør would later develop into the most important town and seaport outside Copenhagen.

In Norse mythology as told in the Gylfaginning, the island was created by the goddess Gefjun after she tricked Gylfi, the king of Sweden.

[6] However, since modern maps show a similarity between Zealand and the Swedish lake Vänern, it is sometimes identified as the hole left by Gefjun.

Gefjun is queen of King Skjöldr, eponymous ancestor of the Scyldings, related to the etymological debate.

On 5 June 2007, the regional subsidiary of national broadcaster DR reported that Kobanke in the southeast near the town Rønnede in Faxe Municipality, with a height of 122.9 metres (403 ft), was the highest natural point on Zealand.