Alex Snell said he and partner Leah Martine consider themselves lucky to be alive.
Mr Snell appeared on season five of Netflix’s Too Hot to Handle, a reality dating show.
The pair, both 28, were travelling from Uluwatu to Canggu when their boat, operated by firm GoBoat, got into difficulty. Mr Snell, personal trainer, said he and Ms Martine were then tipped into the water, where they spent half an hour before they were rescued.
The couple’s belongings were ruined and, now back in home in London, they are trying to come to terms with the ordeal.
Mr Snell said: “It was terrifying. I honestly couldn’t believe it was happening. I was in so much shock I could barely register what was going on. The waves were around 18 foot high. They were relentless and just kept crashing.
“I tumbled around in the water. I got stuck under the boat and I couldn’t breathe. I was struggling there for about 30 seconds. When I got to the surface it was another battle to keep up. I was sure someone would have not made it, we were all assuming the worst.
“We were in the water half an hour – but it felt much longer.”
Ms Martine, a campaign manager, said: “I’ve never been so scared in my life – it was my worst nightmare. We honestly thought we were going to die. Waves were constantly going over our heads. It’s been really hellish.”
The couple boarded the boat on 29 September as part of their six-week Indonesia trip. They claim the vessel – which they believe was around 25 feet – started to rock halfway to Canggu, a popular tourist area on the south coast of Bali.
One massive swell then engulfed the boat and tipped it over, sending them and all their belongings overboard. The couple, along with the other passengers and two crew members, had to desperately keep afloat for half an hour, they said, before someone onshore spotted them in trouble and alerted two surfers who came to their rescue.
“It was approaching sunset which was pretty scary. If it had gone dark it would have been even more horrendous,” said Ms Martine.
“I lost Alex immediately. I thought he was dead and he thought I was. If someone hadn’t sent the surfers to help I really don’t know…