A rescued surfer who spent 32 hours stranded at sea has spoken of his ordeal, saying he was convinced he was "going to die".

Matthew Bryce, 23, was found clinging to his board 16 miles off Scotland's western Argyll coast on Monday night (1 May) after going surfing on Sunday morning.

Speaking from his hospital bed in Belfast, where he is being treated for hypothermia, Bryce spoke tearfully of how he watched the sun set for a second time not believing he would survive another night.

"I knew I had maybe three hours and I was pretty certain that I was going to die with that sunset," he told BBC News.

"So I was watching the sunset and I'd pretty much made peace with it all and then a helicopter flew right over. So I jumped off the board and I lifted the board up and I started waving the board in the water and they flew right over, I thought they'd missed me.

"But then they turned round and when I saw them turn it was indescribable. I can't describe it at all. These guys were the most beautiful sight I had ever seen. I owe them my life."

Bryce, from Airdrie in North Lanarkshire, had been surfing on a Westport beach in the Kintyre peninsula at about 11am when he was carried out to sea by the wind and strong currents.

"I couldn't get back in when I was trying paddle," he said. "It was just relentless. So I took a diagonal route southwards and as I was doing that it was still just dragging me out ... and I started to panic."

At one point he managed to get to about a mile from land, only for the tide to change direction. "It got to the point where my paddling was ineffective, but I kept on doing it because it was keeping me warm."

When night fell on Sunday, Bryce was left floating in pitch black waters. "It was incredibly lonely and quiet because there was just nothing – just waves," he said. "I hadn't seen any helicopters. I was thinking I was going to die – I was almost convinced. I didn't think I would see sunrise."

Bryce said he then saw lights from fishing boats and desperately tried – but failed – to signal them for help. By daylight he was starting to pass out through fatigue and fall off his board. His muscles were also cramping up.

When the rescue helicopter did finally locate Bryce and winch him to safety, it was 7.30pm on Monday – 32 hours after he had first entered the water. He had drifted 16 miles off the Scottish coast and was 13 miles off the coast of Northern Ireland. Bryce was wearing a wet suit which doctors say helped save him.

The surfer's parents, John and Isabella, described their anguish as they had waited for news after he was reported missing on Monday.

Describing the moment his phone rang, John Bryce said: "I walked outside the caravan because I think it's the worst news possible. It was the police inspector and all he said was 'he was found alive'.

"I was outside crying my eyes out and obviously Isabella and my son thought we'd received the worst possible news. So I had to run in and tell them 'he's alive, he's talking to the coastguard'."

About half an hour later they were able to speak to their son on the phone.

Bryce said he owed his life to the coastguard, RNLI, the police and the staff at Ulster Hospital. "They are all heroes," he said.

An RNLI lifeboat has since recovered his surf board but Bryce said he was not planning to use it again.

"I think we'll find a good use for it, maybe as starter fuel," he said. Asked if he was finished with surfing, he added: "I think so, I couldn't do that again."