Badeweiher Marl, Bathing lake in Marl, Germany

Badeweiher Marl is a natural pond on the edge of Chemiepark Marl, about 2–3 km from Marl town centre. Its water surface measures 170 by 245 metres. Roughly half was used as a bathing area run by Evonik Industries, while the other half is fenced off as a biotope and is home to grey herons.

Evonik Industries ran the bathing area at Badeweiher Marl for almost 75 years. In 2026 the company announced it would not reopen it, citing its strained finances and the group-wide 'Evonik Tailor-Made' savings programme, which targets annual savings of 400 million euros; operating the lake costs a six-figure sum. The city of Marl, under budget consolidation, could not take over the operation.

The lake draws families and local residents who gather here on warm days for swimming and relaxation along the shores. Its position next to the industrial area makes it a place where leisure and working life meet.

The pond lies 2–3 km from Marl-Mitte and about 7 km from Haltern am See; the water surface measures 170 by 245 metres. Only the bathing half was open to the public, while the rest is fenced off as a biotope. Since Evonik announced in 2026 that it would not reopen the bath, access is no longer guaranteed.

The lake is home to grey herons, and the half that is not used for swimming is fenced off as a biotope. The bathing area was run by Evonik Industries for almost 75 years before the company announced in 2026 that it would not reopen it.