However, using propellers also has its challenges. One issue is the potential for cavitation, which occurs when the pressure drop behind the propeller blades creates bubbles that can disrupt the flow and reduce efficiency. This is more likely to happen at high speeds or in environments with low ambient pressure.

The key advantage of propellers is their versatility. They can be designed to provide both forward/backward thrust and lateral thrust, enabling the robot to perform complex maneuvers such as hovering, ascending, descending, and even rotating in place.

That's correct. Propellers are much more suitable for underwater environments because they can generate thrust in all directions, allowing the robot to maneuver freely in three-dimensional space. Plus, they don't require a solid surface to make contact with, which is often unavailable or uneven in the deep sea.

In most cases, deep-sea robots do not use wheels to move underwater, especially in deep or rough waters. Instead, they primarily rely on propellers for propulsion.