Authorities said they discovered the body near Seawall Road at 7:40 a.m. Tuesday.
According to the Lomita Sheriff's Station, witnesses on a beach reported a swimmer in distress around 6:45 p.m. on Monday approximately 100 yards offshore from Trump National Golf Club.
The swimmer was described as a man in his mid-20s with multiple tattoos, wearing black shorts and black shoes, the Coast Guard said in a statement. He was last seen yelling for help and grasping a pool flotation device.
The swimmer's identity remains unknown. According to the Lomita Sheriff's Station, it is unclear if anybody accompanied the man at the beach.
Officials said two fire department divers searched the water in the area of Portuguese Bend Monday. Several boats and a Coast Guard helicopter were also deployed in the search.