The squeezing ear pain most often occurs near the surface where the relative pressure changes are greatest. Each foot below the surface places continuing pressure on the diver. Normally, the eustachian tube will open and allow the pressure behind the eardrum to equalize with the outside pressure of the seawater in the ear canal. But, if the eustachian tube can't do its job, then as the seawater pressure in the ear canal increases, the eardrum is forced inward, inflaming the eardrum and causing pain. If the pain is ignored and the diver drops deeper, the pressure will continue to increase and the eardrum may burst.
Cold seawater rushes into the middle ear.
Nausea, vomiting, dizziness, and confusion may follow. Rapid ascents or descents in a car or commercial air flight may cause pressure equalization problems in the ear but not to the same degree as in a dive. You may get an ear pop but not an ear squeeze. There are many reasons for the eustachian tubes not to equalize the pressure. At low pressure, the diver has a feeling of fullness.