Many people have trouble clearing their ears as quickly as others. Many divers have felt the added pressure (no pun intended) of feeling like they are holding the whole group up as they try frantically to get that "click" that equalizes pressure between the inner and outer ear. Some are foolish enough to descend with the group anyway and experience damage or rupture to their eardrum accompanied by severe vertigo. If your ears take a bit longer to equalize, tell the divemaster or instructor about it beforehand. She or he can help you to buddy up with someone else who takes longer to clear. Also, if it's a guided dive the divemaster guide will know to wait for your "okay" sign until they start the tour. Tell your dive buddy, especially if you can't find someone else with ear problems. Make sure they know to wait for you instead of swimming off.
If you have a head cold or sinus problems that cause your nose to be stuffed up, you have 2 options: reschedule the dive for when you're better, or take a NON-DROWSY over-the-counter medicine to clear out your passages. If there is too much mucous in your sinus cavities, you aren't going to be able to equalize, period. That's the law of physics.
If you're already in the water and find you can't equalize, go up a couple of feet at a time (slowly!) pinching your nose and trying to blow air out through your nostrils-GENTLY as you continuously exhale. This is a thin membrane of skin, not a PVC sink drain to blast out. Don't give up right away. Keep ascending slowly while trying to clear. If you can't do it, or feel pressure and pain in your ears, abort the dive. If you told your group about your ear problems, they'll be waiting for you. Signal your buddy or the scuba guide by pointing to your ear and shaking your head "No". Make sure your buddy doesn't go on alone. Never try and tough it out--you will destroy your eardrums, literally.
