Bällstaviken, Bay inlet in Huvudsta, Sweden

Bällstaviken is a bay of Ulvsundasjön, itself an inlet of Lake Mälaren. Its outer part is shared between Stockholm and Solna municipalities, its inner part between Stockholm and Sundbyberg. The bay holds industries, green areas and small-boat harbours, and new waterside housing was built on both shores in the late 1990s and early 2000s.

Bällstaviken is the inlet of Ulvsundasjön, itself a bay of Lake Mälaren, with its outer part divided between Stockholm and Solna and its inner part between Stockholm and Sundbyberg. During the late 1990s and early 2000s new waterside housing was built on both sides of the inlet. Its main inflow is Bällstaån, which carries mostly stormwater.

The northern shore of Bällstaviken has a tree-lined promenade that continues along Ulvsundasjön to Hornsberg on Kungsholmen. The inlet's water comes mainly from Bällstaån, which carries stormwater, and Stockholm Vatten rates the bathing water as unfit or fit with remarks.

The inlet is crossed by several bridges that form the main transportation links between Solna and Stockholm for both pedestrians and vehicles. The waterfront paths are well-maintained and accessible by bike, making it easy to explore the shoreline.

Bällstaviken's main inflow is Bällstaån, whose flow consists mainly of stormwater. According to Stockholm Vatten, the bathing water quality there is either unfit or fit with remarks, so the inlet is not a reliable swimming spot despite its waterfront paths.