An air conduction system includes an air collecting chamber, a first air inlet, an additional air inlet, and a buoyancy body. Air is supplyable to the air collecting chamber by said air inlets. The first air inlet has an air control valve via which the air inlet is selectively closed. The additional air inlet has an additional air control valve via which the additional air inlet is selectively closed. A buoyancy body is provided which is movable via a geodetically rising water level and which is operatively connected to a closure element of the air control valve of the first air inlet. The closure element is convertible from an open state, in which the first air inlet is fluidically connected to the air collecting chamber, into a closed state, in which said fluidic connection is interrupted, when the water level rises. The closure element comprises the buoyancy body.