Failure to equalize is an inherent and continuous risk on every dive you will ever make. I refer to this as Equalization Risk.
A diver can injure their ears during the initial descent (when pressure changes are greatest), or at any other time during the dive. Effective management of this risk requires that you develop keen ear-monitoring skills (situational awareness) and good technique. And since safety is always the primary objective on every dive, a diver must be prepared to abort a dive if they are unable to equalize fully.
Over the course of my diving life (30+ years) I've experienced and witnessed many ear injuries. A high percentage of these injuries happened during the confined water segment of the Open Water course, in pools where the bottom was less than 5m/15feet deep. It's at this stage that the student is making their first attempts to equalize while possessing no developed buoyancy control skills and very little situational awareness.
It's a painful experience for the unfortunate victim of an ear injury, with outcomes ranging from a mildly annoying weeklong feeling of fullness and dull hearing, through to punctured ear drums, bleeding ears, near drowning, and permanent damage.
PADI Open Water course materials highlight and emphasize the importance of full and proper equalization of your ears on descent and what to do in the event of a reverse block on ascent. At VSds, we think that every novice diver ought to have a full medical and physiological understanding of what's going on in your ears when you go underwater.
The following article is taken from the Divers Alert Network (DAN) website. We urge you to read it closely and practice the various techniques at home. And we urge you to check out DAN. Click on images to expand.