Exactly ten years ago today, December 26, 2004 when a 9.3-magnitude earthquake off Indonesia's western tip generated a series of massive waves that pummeled the coastline of 14 countries as far apart as Indonesia, Thailand, Sri Lanka and Somalia.
At the memorial today, prayer recitals and solemn visits to mass graves marked the start of mourning of over 22,000 people that perished at the decimated coastal areas of the Indian Ocean a decade ago.
Among the victims were thousands of foreign tourists enjoying Christmas in the region, carrying the tragedy of an unprecedented natural disaster into homes around the world.
A chorus of voices singing the Indonesian national anthem marked the start of the ceremony at a 20-acre park in Indonesia's Banda Aceh -- the main city of the province closest to the epicentre of the massive quake and which bore the brunt of the destructive waves. The Indonesian national anthem was sang simply to accommodate all because it was a worldwide calamity.
"We are gathered here today to remember the historic disaster that took place on December 26. As we know, it was one of the biggest to have ever happened on our Earth," Aceh governor Zaini Abdullah told the crowd of several thousand including dignitaries gathered for the official memorial.
"The disaster was also an awakening -- to be aware of our environment and to continue to be vigilant and understand how to deal with disasters," he said.
"Learning from our experience, we call for strengthening of solidarity in handling disasters to lighten the load of disaster victims across the world," he said, hailing the outpouring of aid from local and foreign donors.
Mosques also held prayers across the province early Friday while people visited the mass graves -- the resting place of many of Indonesia's 170,000 tsunami dead.
Also in southern Thailand, where half of the 5,300 dead were foreign tourists, a smattering of holidaymakers gathered at a memorial park in the small fishing village of Ban Nam Khem, in a reminder of the global scale of the disaster.
"Everyone knew someone affected by the tsunami, I knew people too. We want to show our respect," said Agnes Moberg, 18, from Sweden, which lost more than 500 of its nationals and was due to honour its dead later Friday.
Another closely affected woman, Somjai Somboon, 40, said she was yet to get over the loss of her two sons, who were ripped from their house when the waves cut into Thailand.
"I remember them every day," she told AFP, with tears in her eyes.
The scale of the tragedy emerged in the hours and days after the waves struck.
Disaster-stricken nations struggled to mobilise a relief effort, leaving bloated bodies to pile up under the tropical sun or in makeshift morgues. According to one of the volunteers, who worked for hours non stop, "This is a sight that I will never forget in my lifetime, no, not even when I,m sleeping"
The world practically poured inn money and expertise into the relief and reconstruction, with more than $13.5 billion collected in the months after the disaster.
Almost $7 billion in aid went into rebuilding more than 140,000 houses across Aceh, thousands of kilometres of roads, and new schools and hospitals.
The number of children that perished in the disaster, runs into tens of thousands. the disaster also brought to an end a decade-long separatist conflict in Aceh, with a peace deal between former rebels and Jarkarta effected less than a year later.
Sri Lanka is also not left out, as preparations are on top gears to hold a memorial for the 31,000 people who perished. the memorial is to hold a at a railway site where waves crashed into a passenger train, killing 1,500 people.
Ahead of the ceremony a train guard who survived told AFP a lack of knowledge of tsunamis -- in a region which had not experienced one in living memory -- led to more deaths than necessary.
"We had about 15 minutes to move the passengers to safety. I could have done it. We had the time, but not the knowledge," 58-year-old Wanigaratne Karunatilleke said.
To plug that gap a pan-ocean tsunami warning system was established in 2011, made up of sea gauges and buoys, while individual countries have invested heavily in disaster preparedness.
But experts have cautioned against the perils of "disaster amnesia" creeping into communities vulnerable to natural disasters.