Abstract: The vessel has an open top receptacle that is provided with a drink-through cap unit removably secured to the upper end of the receptacle. The cap unit includes a cap and a battery-powered mixer incorporated into the cap. An elongated mixing element of the mixer projects downwardly from the cap into the receptacle for agitating and mixing the contents when a switch on the cap is actuated by the user. Without removing the cap unit from the receptacle after mixing, the user may drink the contents directly from a lip on the drink-through cap. A stopper for the drinking orifice in the cap may be mounted on a rockable operating lever that is easily manipulated by the user between open and closed positions.