Surfer's ear is the common name for an exostosis or abnormal bone growth within the ear canal. Surfer's ear is not the same as swimmer's ear, although infection can result as a side effect.
Irritation from cold wind and water exposure causes the bone surrounding the ear canal to develop lumps of new bony growth which constrict the ear canal. Where the ear canal is actually blocked by this condition, water and wax can become trapped and give rise to infection. The condition is so named due to its prevalence among cold water surfers. Warm water surfers are also at risk for exostosis due to the evaporative cooling caused by wind and the presence of water in the ear canal.
Most avid surfers have at least some mild bone growths (exostoses), causing little to no problems. The condition is progressive, making it important to take preventative measures early, preferably whenever surfing. The condition is not limited to surfing and can occur in any activity with cold, wet, windy conditions such as windsurfing, kayaking,sailing, jet skiing, kitesurfing, and diving.