If a diver experiences a "wet" breathing regulator, what is a likely cause?

When a diver experiences a "wet" breathing regulator, one likely cause is an exhaust valve that doesn't seal properly. The exhaust valve is responsible for allowing exhaled air to exit the regulator while preventing water from entering. If this valve is damaged, worn, or improperly seated, water can seep into the breathing chamber, leading to a sensation of breathing in water, or a "wet" regulator.

While a damaged mouthpiece can also contribute to discomfort and may allow slight amounts of water entry, its primary function is to interface with the diver's mouth, not to control the flow of air or water. An open downstream valve does not directly relate, as it refers to how the regulator controls airflow rather than preventing water entry. Therefore, the most relevant cause for a "wet" regulator sensation stems from the exhaust valve malfunction.