Theo Mavromatis, 49, was one of four men aboard a yacht that broke up during a race from Newport Beach to Ensenada late last month. The bodies of the other three men were recovered that same day.
The San Diego County medical examiner's office says a fishing boat crew discovered the body Sunday near the rugged Coronado Islands in Mexican waters south of San Diego.
The man appears to have been 45 to 65 years old but authorities say his identity and the cause of death must await further examination.
A GPS tracker showed a course directly into an island but other theories include a ship collision.
The Associated Press contributed to this report.