The chosen site for the water sports centre was on a natural headland, with superb views overlooking the Vexin hills on the other side of the river Seine. Our proposal aimed to open up the viewpoint from the Quartier des Peintres to overlook the natural world and waterway beyond, using a style of architecture hinging on transparency and gradations, setting up a series of optical filters between the solid, functional nature of the city and the peaceful rolling hills of the countryside. The building’s architectural design embodies this gentle transition: the planted roof echoes the hillsides of Vexin, while the curves of the giant lattice structure, protecting the glass front on the city-facing side, evoke waves in the water, along with the undulations of the roof. These waves also serve a functional purpose, acting as a symbolic marker of the borders between the successive worlds the users pass through as they leave the city behind to become immersed in the waters and the rolling hills of Vexin.