See uber Luft (Lake over Air)

Location: Lake Luzern, Switzerland. Floating construction of wood and two layers of plastic sheet (and water and air). In order to make it float, the air is trapped under the bottom layer of plastic sheeting. This was done by holding the structure some 40 cm above water level and letting it drop, causing an air pocket. The lake water was then poured into the top level of plastic sheeting.