A pair of horseback riders discovered a body floating in the water near Border Field State Park in Imperial Beach Saturday Evening.
The body was discovered partially in the water just before 5 p.m. by two women riding horses near the Imperial Beach shoreline, the San Diego Sheriff's Department (SDSO) said.
The location was less than a half-mile from the U.S.-Mexico Border.
SDSO detectives were working to identify the man, who was wearing swim trunks.
Imperial Beach Lifeguards and firefighters responded to the scene just after 5 p.m.
No other information was available.