Ostseebad, Baltic Sea beach in Flensburg, Germany

Ostseebad is a sandy beach along Flensburg's Baltic Sea coast where visitors swim and relax on wide open spaces. The location features multiple access points and facilities including changing rooms and showers.

In 1872 the Flensburg physician Peter Henningsen and local merchants founded the Ostseebadgesellschaft, which bought land by the Klueser Wald. The bathing establishment opened in 1873, with two bathing bridges and a ship pier for fjord steamers. The city took over the bath in 1880, and in 1905 the beach and restaurant moved slightly north when the waterworks was expanded.

The name Ostseebad (Danish: Østersøbadet) means "Baltic Sea bath", though the site lies on the Flensburg Fjord and never held official seaside-resort status. The Sophienquelle spring below the slope is named after Peter Henningsen's wife and flows again since its 1984 restoration by the Verschönerungsverein.

The beach is reached via Ostseebadweg, laid out in 1875 as a link from Aabenraavej, and the street Am Ostseebad followed in 1878. Free parking is available on site, along with a playground, beach volleyball courts, a barbecue area, a kiosk, a restaurant, toilets and showers. The water stays shallow for many metres out, reaching about 1.50 m at the end of the bathing bridge, so jumping from the bridge is forbidden. The neighbouring Wassersleben beach, chargeable, lies a short walk away along the water.

The water stays shallow for many metres out from the shore, so bathers can still stand far from land; near the end of the bathing bridge it is mostly about 1.50 m deep. Jumping from the bridge is forbidden because of serious accidents, and the beach has at times been watched over by the DLRG.