Emergency services were called to Porth Neigwl (Hell’s Mouth), near Abersoch, on Friday following reports of three people in difficulty in the water. Medics fought for more than an hour to resuscitate the man while the family looked on.
HM Coastguard said it had been called at around 2.30pm.
A spokesperson said: “Coastguard rescue teams from Aberdaron and Abersoch were sent alongside the search and rescue helicopter from Caernarfon, the Welsh Ambulance Service and North Wales Police.”
The beach is known for its on-shore winds and difficult swimming conditions and is popular with surfers and water sports enthusiasts.
One surfer said he was “terribly sad and emotional” following the incident.
Bryn Dando, 45, filmed the coastguard helicopter landing before realising what was happening.
He said: “There was a crowd of people surrounding someone on their back on the beach.
“The paramedics from the helicopter were racing across the beach – several of us ran over with towels to keep him warm.
“Other surfers had brought their boards and formed a windbreak around him.
READ MORE: South Wales Police arrest 3 people on suspicion of murder
“They kept on changing over as they were getting exhausted.
“It takes a lot of physical effort to maintain CPR for that length of time.
“They did everything they could, but he was gone.
“I’ve never witnessed something like that before.
“I just had to go and find a quiet spot and have a little cry.”
The surfer said the incident had prompted him to buy a buoyancy aid and he enrolled on a first-aid course.
He added: “The wind was blowing at about 20 knots, so surfers were offering their towels to try and keep the man warm.
“Another comforted his daughter, who was wrapped in a towel shivering and crying.”
Writing on Facebook, in the aftermath of yesterday’s tragedy, one regular visitor said: “Such powerful rips there. Swim along the beach, not into the beach if you get stuck or it could drag you out.
“Easier said than done, I know. So sorry for the people involved.”
Another wrote: “Oh that’s awful. I have always wondered about the safety of Hell’s Mouth as we were always told not to swim there years ago.
“And yet recently it seems top have been accepted as a place to swim.”