A 17-year-old boy has died after he and two teenage girls were caught in a rip current off the coast at Whitby while out on an inflatable dinghy.
The boy was recovered by lifeboat and airlifted to Scarborough Hospital where he later died.
It is thought he had initially pulled himself to safety but returned to the water to try to help his friends.
The girls, believed to be aged 16, were taken to hospital with hypothermia. All three are from the Tyneside area.
They were treated and discharged from Scarborough District Hospital on Wednesday evening, police said.
The RNLI said the three had been using the dinghy close to Whitby's West Pier.
They said it was thought the boy had managed to pull himself to safety using the ladder on the pier wall, but had returned to the water to help his companions.
After taking the boy to hospital the RAF helicopter returned to the beach to pick up the two girls.
Lifeboatman Hugh Ramsden said they tried to resuscitate the boy after recovering him from the water.
He said: "He was brought back to the Whitby lifeboat house and our coxswain took over CPR... until the emergency services arrived."
North Yorkshire Police said their inquiries into the incident were ongoing.
Humber Coastguard said the girls had swallowed a lot of salt water and were also being treated for secondary drowning, a condition in which fluid enters the lungs and can cause delayed drowning.
The coastguard said it received multiple 999 calls at about 1245 BST requesting urgent assistance as three teenagers were being swept out to sea and in distress.
Philip Rooks, who was at the beach with his children, said he was walking along the pier when his group noticed the teenagers were in difficulty.
He said: "People started to shout to ask if they needed assistance but it was at least 10 minutes before we realised how much difficulty they were in.
'Struggling to survive'
"As my friend and I got a life-ring, people started to phone the coastguard.
"We tried to throw the ring as close as possible but they were some distance out, I think two life-rings were deployed in the water."
He said they watched the boy swim to one of the girls who "was in real distress, shouting that she couldn't swim".
He added: "The poor lad managed to stay with her for a short time but after a couple of waves washed over him he turned in the water face down.
"At this point two life guards were swimming out against what I can only imagine being a strong current.
"Everyone started to shout to the young girl to turn her friend but you could see that she was struggling to survive herself."
The rescue operation involved RNLI lifeguards, the inshore lifeboat, an RAF helicopter and the coastguard rescue team.
Watch officer Katie Gellatly said: "This is a tragic incident which has resulted in the loss of a young life.
"With the bank holiday weekend approaching, we urge all water users to be aware of the inherent dangers of the sea and to be mindful of weather conditions and any warning signs."