The invention relates to a flotation device for use in retrieving an object that is dropped in water. According to the invention the flotation device comprises attachment means and a holder that is resistant in regard of spray water and atmospheric humidity. The holder comprises an inflatable body of a substantially waterproof and air-impervious material, and gas-forming reagents within the inflatable body. The inflatable body is sealed off from the rest of the interior of the holder by means of a narrow seal. In the event of activation of the flotation device, water ingresses in the holder and through the seal and comes into contact with the gas-forming reagents. The formation of gas required for the exertion of a flotation or driving force occurs within the inflatable body itself. The formed gas inflates the inflatable body.