Some 170,000 lives were lost in the country when a 9.1- magnitude "megathrust" quake struck Aceh, a predominantly Muslim province in the northern tip of Sumatra island, bringing about massive waves that also hit coastal areas as far away as Somalia.
"I came here every year to pray for my children, daughter-in-law, and their three children," Maryam, who goes by one name, told AFP, at the Ulee Lheue mass grave, where 14,800 people were buried.
Graves across the province, including in Siron in Aceh Besar district where more than 46,000 were buried, were crowded with people who scattered flowers on the earth where they believe the remains of their loved ones lie to rest.
Survivors then gathered at a mass prayer in Ulee Lheue mosque, one of the few sea-front mosques still standing in the region after the tsunami.
Indonesia sits on the Pacific "Ring of Fire", where the meeting of continental plates causes strong seismic activity, and is frequently hit by earthquakes.
The tsunami commemoration comes just weeks after a strong 6.5-magnitude shallow quake struck inland in Pidie Jaya, a district in Aceh, killing more than 100 people, levelling hundreds of buildings and displacing nearly 84,000 people.
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