Protecting your ears and sinus is critical, and as discussed one of the greatest stressors placed on divers is their exposure to pressure changes at depth. One of the most common injuries as a result of this pressure is barotrauma. There are many types although the most common is inner ear. This occurs when your fail to equalise your ears when you descend.
As you descend the pressure increases on your ears because of the increased water pressure. Overcoming this is quite easy and with practice will become second nature. The most important thing to note is to never ignore the sensation and let the pressure build. If you do you can cause permanent or temporary damage.
So how do we equalise our ears when we feel ear squeeze when diving? The simplest method and one that you will be taught on your open water course is to pinch your nose and gently blow. Another method is to swallow or wiggle you jaw that just as you would on a plane.