Police divers are continuing the search for a missing 14-year-old boy swept out to sea off north Wales on Thursday while swimming with his two brothers.
A major search operation is underway to find the boy
They are checking underwater pipes and cables in the area he was last seen.
Coastguards, the RNLI and the RAF spent the night searching for the boy from Hagley, in Worcestershire.
He and his two brothers got into difficulty off Llandanwg beach, Harlech. One is uninjured while the other is in a critical condition.
The eldest, aged 19, swam to shore and raised the alarm. His 16-year-old brother was rescued by the coastguard about half an hour later at about 2045 BST.
The 16-year-old boy was taken to hospital in Bangor by helicopter, where he is in the intensive care unit in a critical but stable condition. His parents are at his bedside.
Rescuers spent the night looking for the teenager
Coastguards from Holyhead, Harlech and Barmouth, an RAF rescue helicopter and RNLI lifeboats from Criccieth and Barmouth are all involved in the search, which now extends from Barmouth in the south to Criccieth in the north.
A spokesman for North Wales Police said: "Three teenagers, aged 19, 16 and 14, who were on holiday from the West Midlands, entered the water at a point near a beachside cafe.
"After a while they apparently got into difficulty. The 14-year-old boy was swept away by the tide."
Carl Hiltunen, Holyhead Coastguard watch manager, said on Friday morning: "The temperature in the water is about 16 degrees at the moment which probably the warmest of the year but even so we are limited on time on how long someone can survive in these waters.
"We will continue the search and then make a decision later on about how long we are going to continue because each minute that passes diminishes the chance of survival.
The major search off the north Wales coast is the second in a week - on Monday, 12-year-old Sarah Louise Roberts drowned after being swept out to sea, while playing at Newborough on Anglesey.
She had been on the beach at Llanddwyn island, off Newborough, with her foster family.