Coastal protection in the northeast of the island Helgoland is being adapted to the rising sea level and the design sea sate by the Schleswig-Holstein coastal authority (Landesbetrieb für Küstenschutz, Nationalpark und Meeresschutz Schleswig-Holstein (LKN.SH)). For this purpose, small-scale tests are being carried out in a wave flumeat the Leichtweiß-Institute for Hydraulic Engineering and Water Resources to select suitable design variants for the northeast dike. The preferred variants are then examined in large-scale tests in the twin wave flume with regard to hydraulic function and stability. The objective is the reduction of the wave overtopping rate while keeping the crown height as low as possible. This is done by the step-by-step optimization of the geometry in joint coordination between the LKN, the planning office INROS LACKNER SE (IL) and the project partners of the Coastal Research Centre (FZK). For this purpose, the wave overflow rates of the individual variants as well as the forces and moments on crown wall and other structural elements are determined.