Mälaren Valley
Sweden
The Mälaren Valley (Swedish: Mälardalen), occasionally referred to as Stockholm-Mälaren Region (Stockholm-mälarregionen), is the easternmost part of Svealand, the catchment area of Lake Mälaren and the surrounding municipalities. The term is often used interchangeably for the extended capital region of Sweden as Stockholm is located at the lake's eastern end, at its outlet in the Baltic Sea.
Data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).