What is the main advantage of using a surface-supplied system in commercial diving?

The main advantage of using a surface-supplied system in commercial diving is that it reduces the risk of drowning in case of equipment failure since the diver is tethered. This system provides a continuous supply of breathing gas from the surface, allowing the diver to have an umbilical connection to the surface that includes not just the air supply but also communication lines and other necessary supports.

Because the diver is physically connected to the surface, there is a greatly diminished risk of losing buoyancy or the ability to ascend safely in situations where there might be an equipment malfunction, such as a faulty regulator or gas supply line. This tethering ensures that the diver can be quickly assisted or retrieved by surface personnel if needed, significantly enhancing safety during underwater operations.

While other options may highlight benefits associated with surface-supplied systems, such as dive duration, underwater visibility, and depth capabilities, those factors are not as directly tied to the essential safety component provided by the tethered connection this system offers. Thus, the critical advantage in terms of safety and risk management is the substantial reduction in the likelihood of drowning due to equipment failure.