The most common disease of the outer ear is called swimmers ear, or external otitis (otitis externa).
As the name suggests, it happens when water gets into the outer ear (see structure and function of the ear) and causes an infection. This is much more common in the summer when people are actively swimming.
The symptoms of swimmers ear include an ear blockage and hearing loss associated with pain and, occasionally, foul smelling drainage.
Treatment includes cleaning the ear canal and applying a topical antibiotic ear drop. In more severe cases an oral antibiotic may be indicated. The hearing loss is a conductive hearing loss (see types of hearing loss) and should resolve completely when the ear infection is cured.