A buoyancy compensator vest for providing adjustable buoyancy at various underwater depths by having a back portion for supporting an air tank and an air bladder for inflating and deflating, a portion of the air bladder of which is situated in the arms which surround the waist of the wearer. The improvement of an adjustment strap which can provide continuous variation within limits, of the reach of each of the inflatable arms of the vest whereby the girth of the vest can be continuously and uniformly adjusted to accommodate a wide range of body sizes, in particular waist sizes.