Why is it imperative that the head cushion fits properly?

The significance of the head cushion fitting properly relates directly to maintaining a good seal to the oral-nasal area. An effective seal is crucial in surface-supplied diving systems, as it prevents the ingress of water and ensures that the diver can communicate effectively and safely. A proper fit allows for the integrated systems, such as the communication apparatus and breathing gas supply, to function optimally without any leaks, which can compromise the diver's safety and performance underwater.

This strong seal is also essential for preventing water from entering the helmet, which can lead to a dangerous situation if the diver is unable to manage the water intrusion while underwater. Therefore, ensuring that the head cushion fits correctly is fundamentally linked to the overall safety and functionality of the diving equipment.