Indonesia and several other countries badly hit by the Boxing Day Tsunami in 2004 are marking the anniversary of the devastation.
The tsunami, triggered by a 9.3-magnitude earthquake a decade ago, killed about 230,000 people across several Asian nations along the shore lines of the Indian Ocean.
The Indonesian province of Aceh witnessed the maximum wrath of the disaster claiming 168,000 lives.
Thousands gathered in the provincial capital Banda Aceh's Great Mosque, one of the few buildings which survived the killer waves, to commemorate the anniversary.
"The reason is because this is the house of Allah. Allah kept his house unscathed, that's what we Muslims believe," said Azman Ismail, the Grand Imam of the mosque.
"After the tsunami, no-one fights against each other, people live in harmony and peace till this day," he said, referring to tsunami ending the decades-long conflict in the region. A peace deal was secured between the government and the rebel forces eight months after the tsunami hit the area.
Aceh governor Zaini Abdullah, who was leading the events at the mosque, said: "The tsunami had caused deep sorrow to Aceh residents from having lost their loved ones. Sympathy from Indonesians and the international community has helped (Aceh) to recover."
Similar events are also taking place in Thailand and Sri Lanka where thousands of people were killed.
Prime Minister David Cameron in a statement on the anniversary said: "At this poignant time, my prayers are with all those remembering people who were caught up in the disaster, including the 151 British nationals who lost their lives."
"In the face of tragedy and adversity, hundreds of thousands of people have demonstrated real resilience to rebuild their lives and millions more have shown extraordinary generosity to help those affected."