An automatic inflatable personal flotation device configured to be thrown to a person in a body of water to assist that person with staying afloat while waiting to be rescued. The flotation device is provided in a substantially baton-shaped configuration having a handle that is easily and effectively thrown and a flotation bladder at one end of the handle. A cylinder of carbon dioxide is disposed inside the handle. An inflator assembly is operatively connected to the cylinder to automatically activate upon contact with water so as to release pressurized gas and rapidly fill the flotation bladder. A water dissolvable mechanism can be utilized as the operable mechanism for the inflator assembly. Preferably, the cylinder is disposed in a support tube and the handle is made out of insulating material to thermally insulate and protect the cylinder from cold and hot temperatures and contact with objects while stored or transported.