Abstract: This subsea exploration apparatus comprises a ballast tank and a shuttle (7) with a watertight enclosure (10) which contains instrumentation for measurement, control and transmission of signals to a surface buoy. The enclosure is guided along a cable (1) fixed to the ballast tank and is provided with a chamber (26) whose lower opening is equipped with a hatch (29). When the shuttle is in high position, a load of ballast is transferred from the tank (5) into the chamber (26), causing the shuttle to descend. This load is jettisoned in a low position of the shuttle, by opening the hatch (29), in order to permit it to reascend.