Meander fish passes, Fish ladder in Schwentinental near Kiel, Germany.

The Meander fish passes near Schwentinental form a spiraling channel with 36 basins arranged in a circular pattern over roughly 200 meters. This structure allows fish to navigate around the Rastorfer Mühle weir on the Schwentine River.

Construction began in 2004 at the Rastorfer Mühle power plant, with operations starting the following year. The project was developed to give migratory fish access to their upstream spawning grounds.

The spiral pass drew public criticism: the Bund der Steuerzahler and the Landesnaturschutzbund Schleswig-Holstein called the first implementation a waste of taxpayers' money. Architect Hans Wilhelm Peters designed and patented the meander fish pass at Bochum University of Applied Sciences.

You can view the structure from outside, and it is easily accessible for observation of the spiral design. Spring and fall offer the best times to visit, when fish migrations are most active.

The first Helix-Turmfischpass was built at the Raisdorf II power station of the Rastorfer Mühle works, and the design by architect Hans Wilhelm Peters was patented. The Bund der Steuerzahler and the Landesnaturschutzbund Schleswig-Holstein called the roughly 550,000-euro, mostly EU-funded project a waste of taxpayers' money.