A lot of divers have problem with their ears not equalizing and hurting when they go diving.
Dr Edmund Kay - a doctor and diver for over 20 years - explains the problem and the different ways to overcome it. He also explains why trying to equalize - when you're below 10m - by vigorously blowing your nose is a bad idea.
See the video here: http://faculty.washington.edu/ekay/
Thanks to Bianca for listing this video on her site!! Thanks Bianca!!