Equalising correctly will improve your dive experience
Let's go through some fundamental diving physiology. The eardrum seals the middle ears, but the eustachian tubes, which go to the back of your throat, connect them to the outside. Water pressure bends the eardrum inward as the air in the middle ear compresses as you drop. You equalise or "pop" your ears by sending air into the middle ear via the eustachian tubes to replace volume lost to pressure. Failure to do so can cause ear pain during diving, as well as harm to the sensitive systems of the ear.
You can blow by exhaling (Valsalva Maneuver) or by utilising your neck muscles (Frenzel Maneuver), with the latter being preferable since it is softer and easier to regulate. You may already be doing it: exhale completely as much as you can at the surface, squeezing out as much as you can, then squeeze your nose and softly pop your ears. If you're equalising with your throat rather than exhalation, you won't be able to exhale. Many divers can also equalise by swallowing, wriggling, or expanding their mouths, or a combination of these techniques. Sucking while pinching your nose is also an option.
The key to safe equalisation is to get air to flow from the throat to the ears via the typically closed eustachian tubes opening. Most divers are trained to equalise their breathing by squeezing their nose and gently blowing. The eustachian tube is gradually opened, allowing air to pass to the middle ear.
Ear Pressure Equalization Suggestions
Make sure you hear/feel the "pop" in both ears when you swallow, expand your jaw, or lightly squeeze and blow before getting on the boat. This indicates that both of the eustachian tubes are opening.
Begin slowly equalising your ears every few minutes many hours before the dive. Gum chewing appears to assist some people because it forces them to swallow more often.
Equalization requires greater effort when you're feet up than when you're feet down, according to studies, but this isn't an issue for most dives.
Stay Ahead of the Game
Early and often, equalise the pressure, keeping up with it as you drop. Don't wait until you're in a lot of pain, discomfort, or pressure. As soon as you notice tiny pressure variances, equalise.
If it causes you pain, you should stop.
You should not experience discomfort if you equalise properly and frequently enough. Because of the pressure disparity, delaying equalisation might cause your eustachian tubes to get blocked. Ascend a few feet and attempt again to equalise.
Stop diving if you can't equalise your ears.