A boy who was playing in a cove slipped from rocks and drowned despite efforts of his nine-year-old friend to rescue him, an inquest heard.
Dillan Brown, 13, from Llandudno was with his friend on 4 May at the town's Great Orme when he fell into the sea.
His friend, who cannot be named, managed to drag him from the sea and tried to give CPR up to 10 times before going for help.
The coroner said Dillan's death had been a "very unusual incident".
The inquest in Llandudno heard from the friend that Dillan had been on rocks near the water's edge in Pigeon's Cove in the early evening and was "messing about dangling his feet off the edge".
He slipped and fell into the water, and the boy heard several cries for help before a big wave came.
The boy managed to pull Dillan to the shore, although the court heard later it was possible Dillan was in the water for as long as 40 minutes before his friend could get him out.
The boy tried between five and 10 times to administer CPR before climbing back up to the road, Marine Drive, and stopping a cyclist, Scott Hughes.
Mr Hughes and Steve Hargreaves, another passer-by, made their way to the shore to help Dillan.
Mr Hargreaves said in a statement: "It became quite apparent he was not breathing and I could not feel any pulse."
The men carried out resuscitation until a rescue team arrived. Dillan was airlifted to Ysbyty Gwynedd in Bangor but was pronounced dead at 23:00 BST.
Pathologist Dr Brian Rogers gave a cause of death as drowning as well as cold water immersion.
Assistant coroner David Pojor was told the area was popular with groups of young people but the volume of call outs to the area because of people getting into difficulties was "very low".
Richard Thomas for Mostyn Estates, which owns the land around the cove, said they had never been approached about putting warning signs in the area.
Mr Pojor said he would not write a report calling for signs to be erected because he questioned how practical it would be.
He paid tribute to those who had tried to help Dillan, saying the nine-year-old boy had "acted bravely and responsibly for such a young boy in trying to save his friend".
He recorded a conclusion of accidental death.