Abstract: A breathing apparatus for underwater swimming or diving comprising a ventilating pipe formed with a cylindrical chamber, a buoyancy block disposed into the cylindrical chamber, a plug force-fitted on the top of the cylindrical chamber, a sleeve force-fitted with the center hole of the plug, a rubber tubing connected with the lower end of the sleeve, a movable member having a notch, a cap threadedly engaged with the top of the ventilating pipe, a float body on which is mounted the ventilating pipe, a hose threadedly engaged with the ventilating pipe, and a mouthpiece threadedly engaged with the hose.