BANDA ACEH, Indonesia -- Muhammad Yani stood on the roof of a mosque, watching the tsunami's churning waters surge past, roiling with people and debris.
"I was not afraid at the time," said Yani, 35, who later found out he had lost his parents and younger brother to the waves. "I was more aware than ever that my soul belonged to Allah."
The dried-fish vendor pieced his life back together with a donation of salt and a wheelbarrow, and now lives in a ramshackle hut on a swampy wasteland. He rejected offers of cash -- testimony to the resilience of those who survived the disaster last Dec. 26.
The world united in grief and compassion Monday to remember the devastation wrought in a dozen nations around the Indian Ocean a year ago.
Mourners filled mosques in Indonesia's shattered Aceh province, the region hit hardest. Candlelight vigils in chilly Sweden remembered citizens lost during sunny holidays. An achingly personal tribute -- a bouquet of white roses -- stuck in the sand in Thailand.
In a taped message, President Bush recalled "the acts of courage and kindness that made us proud" in the sorrowful days after the disaster. Former president Clinton, the U.N. special envoy for tsunami recovery, promised not to let the world forget its pledges of aid.
Survivors relived the terrible day when the sea rose as high as 33 feet and surged inland for miles with seemingly unstoppable force, carrying along trees, houses, train cars -- and thousands people -- in a churning rush.
"It was under the same blue sky, exactly one year ago, that Mother Earth unleashed her most destructive power upon us," Indonesian President Susilo Bambang Yudhoyono told a crowd at a ceremony in Banda Aceh, provincial capital of Aceh province, which had 156,000 dead and missing.
He sounded a tsunami warning siren -- part of a system that did not exist last year -- at 8:16 a.m., the moment the first wave hit, to herald a minute's silence.
On Dec. 26, 2004, the region's most powerful earthquake in 40 years tore open the sea bed off the Sumatran coast, displacing billions of tons of water and sending waves roaring across the Indian Ocean at jetliner speeds as far away as East Africa.
The impact was staggering. Water swept a passenger train from its tracks in Sri Lanka, killing nearly 2,000 people in a single blow. Entire villages in Indonesia and India disappeared. Lobbies of five-star hotels in Thailand were filled with corpses.
At least 216,000 people were left dead or missing and nearly 2 million lost their homes in a disaster that still rends hearts.
On Monday, about the time the waves hit a year ago, a man sat alone on Patong beach in Thailand weeping quietly as the sea gently lapped before him. A white rose bouquet jutted from the sand nearby. He refused to talk to a reporter.
Nearby, Ulrika Landgren, 37, had come from Malmoe, Sweden, to see where nine of her friends died. "Somehow it's good to see this place," she said, tears leaking from behind her sunglasses.
Indonesia tested its tsunami warning system for the first time Monday. Alarms sounded in the Sumatran town of Padang, 620 miles south of Banda Aceh, sending residents fleeing for higher ground in a simulation.
"We knew it was just a drill," said Candra Yohanes, 55, who was among those who ran. "Still, when I heard the siren, my heart was pounding so hard."
Dozens of powerful aftershocks have rattled the region since last year's magnitude-9 quake, keeping people anxious about the possibility of another tsunami.
Somber ceremonies were held around the world.
In Sri Lanka, President Mahinda Rajapakse met with survivors near the site of the deadly train accident. Butchers hung up their knives to show respect for life, and Buddhist monks chanted prayers through the night.
Thousands of Indians attended an interfaith service at an 18th century church, then marched to a mass burial ground.
Sweden, Germany, Finland and other European countries held memorials to mourn their dead. The tsunami killed more than 2,400 foreigners, many of them European tourists, in Thailand.
Somalis gathered in mosques along the East African nation's coast to commemorate the 289 people who disappeared in the waves and to pray for the tens of thousands still homeless.
"It was so brutal, so quick, and so extensive that we are still struggling to fully comprehend it," U.N. Secretary-General Kofi Annan said in a videotaped message played in Banda Aceh.
The tsunami generated one of the most generous outpourings of foreign aid ever known -- some $13 billion in pledges. But frustration is growing among the 1.4 million people still living in tents, plywood barracks or with family and friends.
"You want to talk about changes; we've seen nothing," said Baihqi, a 24-year-old Acehnese survivor, waving a hand dismissively at the jumble of scrap iron and plastic sheeting that is all that remains of his neighborhood. "Many promises of aid, but that's all we get -- promises."
The anniversary "just means we've existed for one year," he said.
For most, though, it was a day to think about the hellish events of a year ago, about death, about survival.
On Thailand's Patong Beach, Raymond and Sharon Kelly recalled how she escaped because her husband boosted her onto a wall. He was swept away and washed inside a shop, but managed to open a skylight and get on the roof.
"I never thought I would come back. Every day I would cry," she said.
Despite their fears, the couple from Hull, England, came back to remember and to pay respects to those who were lost.
As they talked, a man tapped Sharon on the shoulder and said, "Remember me?"
It was Adolf Ruschitschka, 69, from Ruesselsheim, Germany. The two had been trapped together on a rooftop ringed by the savage, swirling waters.
Shaking with emotion, Sharon embraced him, tears pouring down her face.