Mälaren

Mälaren, or Lake Mälaren, is a large freshwater lake in eastern Sweden. It is one of the country’s largest lakes by area, lying west of Stockholm and extending roughly from Västerås in the west toward the Stockholm archipelago in the east. The lake drains into the Baltic Sea and forms an important link in the region’s waterway system.

The lake covers about 1,100–1,150 square kilometers and measures roughly 120 kilometers in length from west to east. Its shoreline crosses several counties, including Västmanland, Uppland, Södermanland, and Stockholm. Mälaren receives inflow from multiple rivers and streams in its basin, and its outflow to the Baltic Sea is through waterways that pass through central Stockholm.

Historically, Mälaren has been central to regional trade, transport, and water supply. The city of Stockholm developed on its eastern shores, and for centuries the lake served as a major inland waterway connecting inland towns with the Baltic. In the 20th century, industrial and urban development led to nutrient runoff and eutrophication concerns, prompting wastewater treatment improvements and watershed management efforts to improve water quality.

Ecologically, Mälaren supports diverse fish and bird life, including species such as perch, pike, roach, and zander, along with broader aquatic and littoral communities. The lake is subject to ongoing environmental monitoring and conservation programs aimed at balancing ecological health with recreational and economic use.

Today, Mälaren remains a focal point for recreation, tourism, and urban life in the Stockholm region, offering boating, fishing, bathing, and scenic shorelines for residents and visitors alike.