Jon Lewin, 36, had been visiting the country on holiday with friends from Newquay.
They had gone out surfing early on Sunday morning, but his surfboard was found floating in the water. Nearby doctors were unable to revive him.
Mr Lewin split his time between Bristol, a caravan in the Gower, Wales, and Sri Lanka.
Writing on Facebook, his girlfriend Immy said they were having “the most amazing holiday” before Mr Lewin’s death.
“I am absolutely devastated, words can’t even describe the hole I feel through my heart. He died in the water, doing something he loved.
“He had said to me before that he never felt his seizures coming on so his last moments on this earth would have been surfing a wave in his absolute element, loving life,” she added.
Mr Lewin first visited Sri Lanka in 2004, and was caught up in the aftermath of the Boxing Day Tsunami, which killed more than 230,000 people.
He went on to visit the country several times, often taking surfing pictures for his work and he published a cookbook based on his time there.
Speaking to BBC Radio Bristol in December, Jon talked about his love of surfing.
“I have been surfing since the age of 16.
“It was the one thing that kept me level through my life.
“It has taken me to some amazing places around the world.
“You’re just in that moment, and time slows down, it’s just something that will be with me until I die I imagine.”