In this paper the problem of depth control for unmanned underwater vehicles (UUV) is addressed. The utilization of such robotic vehicles has gained an increasing importance in many marine activities. As the importance and the complexity of the tasks performed by UUV increase, the need for automatic control schemes that guarantee high performances in motion and positioning has become a basic issue in underwater automation. The critical point in the considered application is the reduction of the overshoot in the position response. At this regard, different control schemes, based on PID and fuzzy techniques, are proposed and their performances compared.