The goal of the Flussbad project is the permanent transformation of a 1.5-km stretch of river in Berlin’s historic center that has gone unused for more than 100 years.
The lower section of the course of the river, currently channeled as a canal, will be made into a space accessible to the public via two broad shoreline stairways at the Lustgarten and the Schlossplatz. The design alterations in this sensitive city-planning area, part of which belongs to the “Museum Island”, a UNESCO world cultural heritage site, are restricted to a minimum.
In the former canal in the middle of these historical environs, a new site will be created for sitting, watching, and relaxing. And for swimming.
These stairways provide access to a natural swimming pool 745 meters long, for the water flowing through this arm of the river has bathing water quality. A functional changing facility with lockers serving the practical needs of swimmers is invisibly integrated in the unused lower storey of the former Kaiser Monument.
The filtered water comes from the upper reaches of this section of the river, which lies about 1.2 meters higher than the pool. There, on a stretch 390m meters long, a 7.200m2 constructed wetland is inserted into the canal profile to purify the running water in a natural way. The 640-meter uppermost section of the river that continues from there will be renaturized. To this end, the northern shore wall will be completely removed and the course of the river gently widened into the grounds of the Fischerinsel. As an auxiliary purpose, this section serves as an inner city green area and preliminary water purifier. The actual main purpose of this side arm of the river is as a wildlife refuge, to support the resettling of riparian flora and fauna in the channeled main arm of the Spree River in Berlin’s urban area.
A general “musealization” has been underway since the mid-1990s in Berlin’s city center around the Museum Island. Here, a monofunctional zone has emerged, oriented on tourist-based or politically representative requirements.
Flussbad is a concept to show alternatives for a more mixed usage of this historic (and touristic) area. It is to be realized on a completely unused part of Berlin’s inner city Spree River, which curves the Berlin museum island (very close to the former location of ≥ Kunst und Technik). The project is meant as a module to supply a vital impulse to the historic center. Flussbad aims to diminish the mental division between “everyday Berlin” and the public Berlin belonging exclusively to tourists and federal agencies. It will provide a badly needed recreational facility in this part of the city and return some “authentic life” to Berlin’s museum island, one of Berlin’s most heavily-trafficked tourist destinations with over a million visitors a year. At the same time, Flussbad puts an end to the economic nonsense of a completely unused waterway—the Kupfergraben—transforming the river itself into a strong argument for the quality of living in the inner city again.
The steps necessary to convert the river arm into a swimming pool are surprisingly simple and very cost-efficient. The upper course is used as a reed bed filter, which naturally purifies the water—a barrage at the lower end prevents unfiltered water to backflow. The quay wall along the Lustgarten is transformed into a generous stair providing access to the swimming pool and offers a place to sit, hang out, watch or dry. Limited practical necessities like locker rooms and footbridges complete the system.
With a length over 700 meters, Flussbad would not only be the world’s longest swimming pool, but also would surely become an urban magnet for both tourists and Berliners, as well as a powerful yet charming vehicle for the city’s global marketing.