Fears are mounting for a British sailor who fell from a yacht in the Pacific Ocean almost 500 miles from land.
The US Coast Guard said the 35-year-old man was conscious and wearing a life jacket when he plunged into the sea but has not been found after more than 17 hours of searching.
A woman, also British and described as an inexperienced sailor, was hoisted from the ship by a rescue helicopter on Sunday.
Coast Guard spokesman Eric Chandler said it was unclear why the sailor had fallen overboard and conditions were not particularly bad at 11.30pm on Saturday, when the man tumbled into the water.
Their 38ft vessel, believed to be privately owned, was about 2,000 miles west of the Hawaiian island of Oahu and 500 miles west of the remote Midway Atoll at the time.
Mr Chandler said four navy helicopters were now combing the area, along with two Coast Guard HC-130 Hercules planes from Oahu in Hawaii and a US navy warship which had been diverted to help.
Mr Chandler said: "It's real challenging out there. We can't get our cutters out there."
He added: "I don't know what made the sailor fall overboard. The female with him said he was conscious at the time and he was wearing a yellow life jacket."
The pair were the only two people on the yacht. Mr Chandler said that while the location of the incident was remote, it was not particularly unusual for the yacht to have been so far from shore at that time of day.
The Pacific News Centre website said there were winds of 25mph and 6ft (2 metre) waves at the time of the incident.