What are the most common problems of scuba diving?

The most common medical problems are simple middle ear "squeezes." Squeezes cause pain in your ears. The pain is caused by the difference in pressure between the air spaces of your ears and mask and higher water pressure as you go deeper into the water. Squeezes that affect the inner ear or sinuses are less common.
Cuts, scrapes and other injuries to the arms and legs can be caused by contact with fish and other marine animals, certain species of coral and hazards such as exposed sharp metal on wrecks or fishing line.