On 27 November 2024, he parked his car at Porth Ysgaden near Tudweiliog, on the north side of the Llŷn Peninsula, and was seen alone wearing a wetsuit preparing to go diving.
The alarm was raised when diving apparatus was spotted upside down in the water soon afterwards.
But the inquest heard evidence from Brian Rodgers, a Home Office pathologist who is also a qualified scuba diver, that there were concerns about some of Mr Magyer's diving kit.
"This particular design of equipment is unsuitable for diving in British waters," Dr Rodgers said. "It's actually quite dangerous.
"The mouthpiece can be dislodged from the air supply by sea currents, wave action, even the wake from a passing boat.
"That's almost certainly what happened here."
