Police opened a missing-person investigation as firefighters and the Coast Guard combed North Shore beaches Thursday for a 51-year-old tourist.

The Coast Guard identified the man as Robert Rumburg, who hasn’t been seen since Wednesday, when he told a friend that he was going surfing for the first time. His hometown was not known.

Using the 87-foot cutter Ahi and a MH-65 Dolphin helicopter, the Coast Guard covered 159 square miles in its search Wednesday night. The search was expanded Thursday to an area west of Sunset Beach.

The Coast Guard was concentrating its efforts four miles offshore, while the Fire Department was working close to shore and on North Shore beaches. Fire Department personal watercraft and a helicopter were also being used.

The Coast Guard said the surfer was reported missing at 9:30 Wednesday night. Capt. Terry Seelig, Honolulu Fire Department spokesman, said fire rescue personnel were called at 9:45 p.m. Wednesday by the Coast Guard.

Seelig said authorities aren’t sure whether Rumburg went surfing near Sunset Beach, where he had been staying with a friend. He said there wasn’t much surf at Sunset Beach on Wednesday.

The visitor was supposed to fly to Colorado on Wednesday, his roommate told authorities. She said the man had never surfed before, but was an expert swimmer. Seelig said the woman reported the man missing late in the day when she returned to find his rental car still parked at her house.

The Coast Guard said the man’s friend reported a white surfboard was missing from the house. The surfboard was found at 11:44 p.m. Wednesday near Rocky Point, south of Sunset Beach.

Star-Advertiser reporter Rob Shikina contributed to this report.