What characterizes a surface supply diving system?

A surface supply diving system is characterized by its ability to provide air directly from the surface to the diver through a hose. This type of system ensures that the diver has a continuous supply of breathable air, which is delivered through a high-pressure hose linked to a compressor or other air supply unit located at the surface. This setup allows for extended dive times and is particularly useful in deeper water where traditional scuba gear may have limitations due to air consumption issues and the risks associated with increased depths.

In contrast, other options describe different types of diving systems. For instance, a system for free divers operates without any air supply support, as free divers rely solely on their ability to hold their breath. The use of black or white units indicates traditional scuba equipment where divers carry their own air tanks, which differs fundamentally from surface supply systems where air is provided from above. Lastly, while surface supply systems are indeed widely used in commercial diving, they are not exclusive to commercial applications, as they can also be employed in various recreational and saturation diving contexts.