Mask squeeze is one of the most common ailments for new divers. It occurs as a result of the pressure in your mask not being equalized during a dive, acting as a suction cup and pulling on your eyes and the soft tissue surrounding them. Although it sounds and looks intimidating, fortunately the effects of mast squeeze are primarily superficial.
It is typically new divers that get mask squeeze because they are concentrating on other procedures and tasks during their dive, either forgetting or completely not noticing that squeeze is happening. The best way to prevent injury is to always keep your nasal passages open when diving. If you have a properly fitting mask, exhaling through your nose will decrease your chances of bruising and barotrauma. Never forget the first rule of SCUBA: breathe!
The fit of your mask will play a crucial role in avoiding mask squeeze. Your mask should fit flush against your face and you should be able to achieve a proper seal by simply inhaling through your nose, without the strap over your head. If your mask does not seal against your face when you do so, then it does not fit your face properly, and you will need to choose something else.
In relation to that, mask squeeze can often happen as a result of trying to ensure your mask doesn’t leak. A bit of leakage is common and does not necessarily mean that your mask does not fit properly; most everyone experiences leakage at some point in their dive history. Be sure not to push the mask into your face to try to make a better seal before you go on the dive. If your mask leaks a little on a dive, simply exhale through your nose, tilt your face upwards, and press the top of the frame toward your forehead to crack your mask seal slightly.
It is easy to equalize the pressure right from the beginning by just breathing out of your nose during a descent. This small amount of air pumped into your mask can make the difference between a comfortable, enjoyable dive and a less comfortable one that ends with a face that only a mother could love!