PADI Divemaster Certification Practice Exam

What is the cause of mask squeeze during a dive?

1. Descending without equalizing the mask

2. Pressure from the water on the diver's face

3. Failing to remove excess water from the mask

4. Inadequate ventilation of the mask

The correct answer is: Descending without equalizing the mask

Mask squeeze occurs when the pressure inside the mask is significantly less than the ambient water pressure as a diver descends. When a diver descends, the water pressure increases, and if the air in the mask is not equalized — meaning that the diver has not expelled enough air into the mask to equal the increasing external pressure — the mask can be sucked tightly against the face. This creates discomfort and can cause bruising or even damage to the delicate tissues around the eyes and nose. Equalization of the mask is essential and involves either allowing a small amount of water to enter the mask and then expelling it or simply breathing out gently into the mask to allow it to fill with air, balancing the pressure. This crucial step prevents the mask from squeezing the diver's face as they go deeper. The other choices relate to mask usage but do not accurately depict the mechanism of mask squeeze. For example, pressure from water on the diver's face does not directly cause mask squeeze, as it is the difference in pressure that creates the issue. Proper mask care and fitting help prevent situations that might cause discomfort, but they won't prevent the straightforward physics that results in mask squeeze if equalization is not performed during descent.