Södermalm, often shortened to just Söder, is the southern district of Stockholm City Centre. Overview. The Södermalm district covers the island of the same name (formerly called Åsön), which, however, is not fully separated from the peninsula of Södertörn (or the rest of the Swedish mainland), as water to both its north and south does not flow freely but passes through a lock and a man-made waterway. Södermalm is connected to its surrounding areas by a number of bridges.
https://en.wikipedia.org/wiki/S%C3%B6dermalm