Wanigaratne Karunatilleke knew nothing about tsunamis before a wave of water slammed into his train on the Sri Lankan coast a decade ago, killing more than a thousand people.
With a little more knowledge, the 58-year-old train guard now believes he could have helped the victims of Sri Lanka's worst tragedy escape to safety.
Karunatilleke was among the few survivors of the disaster on the Ocean Queen Express, which has become a symbol of the disaster in Sri Lanka, and will be at the centre of commemorations for the country's 31,000 victims today.
Shortly before the tsunami hit, he says, the train was brought to an abrupt halt by a wave just after Kahawa station, 90 kilometres (56 miles) south of the capital Colombo.
He believes the 15-minute lull that followed could have allowed passengers to escape to high ground, and blames the huge loss of life on a lack of knowledge about tsunamis.
"If I had known about tsunamis," Karunatilleke told AFP in an interview.
"We had about 15 minutes to move the passengers to safety. I could have done it. We had the time, but not the knowledge."
Karunatilleke, who as head guard was responsible for passengers' safety, overruled the signalling system after the first wave and ordered the driver to move, but by then it was too late.
When the tsunami hit, he became trapped inside a compartment that was floating in the water, managing to escape through a window.
The train was rebuilt after the tsunami and since then Karunatilleke, who is still head guard, stops at the exact same spot every year on December 26 to pay his respects to his departed passengers.
This year will be particularly significant, with the Colombo to Matara train making a special journey for passengers to attend Buddhist, Hindu, Christian and Muslim ceremonies planned to mark the 10th anniversary of the disaster.
The tsunami wave first hit Sri Lanka's southeastern coast, travelling across the island at an average speed of about 500 kilometres (300 miles) an hour and killing 31,000 people in a single hour.
Sri Lanka had not been hit by a tsunami in living memory before 2004 and the tragedy became the country's worst natural disaster.
