People in India, Thailand, Malaysia, Sri Lanka and other Indian Ocean nations held memorial services to mark 11 years since the tsunami that killed at least 230,000 people on December 26, 2004.
More than three quarters of the casualties were from or in Indonesia, with waves of up to 35 meters causing massive devastation in the country.
The tidal waves wreaked death and destruction as far away as coastal Africa, in one of the deadliest natural disasters on record.
The region that was hit first and hardest was Indonesia's Aceh province, located at the northern end of Sumatra, which was struck initially by the 9.1-magnitude earthquake that triggered the tsunami, then by massive waves that swept away all in their path.
Aceh Governor Zaini Abdullah and regional officials visited a mass grave of tsunami victims and attended a memorial religious service at a mosque, German news agency dpa reported.
"We can never forget this day. It brings us a lot of pain. My heart sinks as I think of my son," said 42-year-old Anjammal Thangadurai, who lost her 5-year-old son in the tragedy.
Fishermen also stayed ashore Saturday out of respect for the victims, refraining from taking their boats out.
"Fishermen were advised not to go fishing for two days in remembrance of the tsunami," Miftah Cut Adek, a community leader was quoted by news website Detik.com.
Last year, which marked a decade since the catastrophe, Indonesian Vice President Jusuf Kalla led a prayer ceremony attended by thousands in Banda Aceh, during which he and other officials laid flowers at a grave holding the remains of thousands of tsunami victims.
Coastal provinces in south-western Thailand held memorial services for those who died there, estimated at between 5,000 and 8,000 people.
Anniversary events were held at Kamala Memorial Stone, Mai Khao Memorial Wall, Phuket City Hall and Patong Beach in the southern resort island of Phuket.
Ceremonies were also held in resort towns across the Andaman coast from Phang Nga province to the Phi Phi archipelago.
More than $13.5 billion (11.07 billion euros) was collected around the world in the months following the disaster. Almost $7 billion went towards rebuilding more than 140,000 houses in Indonesia's Aceh province.
In 2011, a tsunami warning system was set up across the world's oceans to ensure that coastal residents can be better protected in future.
dr/se (dpa, AFP, AP)