A snorkel is provided on an upper end section of a conduit with an opening for breathing and a valve adapted to open and to close the opening. The valve is pivotally mounted on an upper end section of the conduit via arms integral with the valve. Below the valve, there are provided two or more floats. The respective floats are housed inside an annular housing defined outside the upper end section of the conduit in a manner that these floats may move up- and downward. When any one of these two or more floats is given buoyancy and moves upward, the arms are reliably actuated upward and thereby the valve reliably closes the opening.
