Abstract: The variable-trim jacket for subaqueous use is equipped with an outer air bag partially fastened to the jacket. The jacket is provided, in either or both of its side areas designed to wrap up the diver's abdomen, with at least a pocket adapted to freely hold respective flaps which form a portion the air bag. Flaps are free to slide outwardly or inwardly in relation to the pockets, with the sliding being due to the adjustment variations in the configuration of the flaps, occasioned as a result of an increase or decrease in volume of the survival gas introduced into or evacuted from the air bag.