What is the most important part of the helmet or mask to check before hooking up the umbilical when setting up a dive station?

The most important part of the helmet or mask to check before hooking up the umbilical is the condition of the faceplate. The faceplate is critical because it serves as the primary barrier between the diver and the surrounding underwater environment. A compromised faceplate can lead to water ingress, which can be hazardous since it can affect visibility, create discomfort, and potentially endanger the diver's safety. It is essential to ensure that the faceplate is free of cracks, scratches, or any defects that could impair its integrity.

While the other components such as straps, valves, and neck dams are also important for the overall functionality and safety of the diving apparatus, the faceplate is paramount because it directly affects the diver's ability to see and breathe comfortably. Ensuring that the faceplate is in optimal condition before any dive not only promotes safety but also enhances the diver's overall performance and confidence during the operation.