Abstract: A servicing apparatus for installing a piece of equipment horizontally on a submerged unit and for removing it therefrom, comprises a movable servicing module designed to engage on the upper part of the submerged unit, pivot thereabout and lock against it in a horizontal position, and a cradle supporting the piece of equipment. The cradle is carried, by means of connections allowing transverse adjustment, by sliding supports mounted in the servicing module, and movable longitudinally by means of jacks. Mutual engagement means are provided on the submerged unit and on the piece of equipment to ensure that the latter is positioned accurately on the unit.