Beside gentle seas that belied the fury unleashed last Dec. 26, survivors, friends and relatives commemorated the lost lives and destruction from one of the worst natural disasters in memory. World leaders sent condolences.
In Indonesia's Aceh province on Sumatra island, the closest land to the magnitude 9 quake that spawned the waves, the president sounded a tsunami warning siren to start a minute's silence at 8:16 a.m. (0116 GMT) — the moment the first wave struck.
"It was under the same blue sky, exactly one year ago that mother earth unleashed her most destructive power upon us," President Susilo Bambang Yudhoyono said. "The assault began with a massive earthquake but ... that was only a prelude to the horrific catastrophe to come."
Similar silences were observed in Thailand and Sri Lanka, where President Mahinda Rajapakse joined ceremonies near the site where the raging waves swept a passenger train from its tracks, killing nearly 2,000 people.
In India, thousands took part in interfaith prayers at an 18th century church, then marched to a burial ground for tsunami victims.
Muslim, Christian, Buddhist and Hindu prayers services were being held across the tsunami zone; flags were lowered to half-staff, and bells rung.
Some preferred more personal reflection.
On Thailand's Patong beach, one man sat weeping in the sand before a gently lapping sea, a bouquet of white roses in front of him. He declined to talk to a reporter.
He was among hundreds of Westerners, including survivors and relatives of those killed, who traveled to sites along Thailand's world famous beachfront where their loved ones died or disappeared.
"Somehow it's good to see this place," said Ulrika Landgren, 37, of Malmo, Sweden, tears leaking from behind her sunglasses as she visited the beach where nine family friends died.
Last year's Dec. 27 quake — the most powerful in 40 years — ruptured the sea floor off Sumatra, displacing billions of tons of water and sending 30-yard-high walls of water roaring across the Indian Ocean at jetliner speeds.
Their impact was staggering.
The tsunami swept away entire villages in Aceh and Sri Lanka, swamped five-star resorts in Thailand and surged into coastal communities from India to east Africa.
On that day, Muhammad Yani clung to the second floor of an Aceh mosque, watching waters full of people and rubbish roil past him.
"I was not afraid at the time," said Yani, 35, who later learned that his parents and a younger brother were killed. "I was more aware than ever that my soul belonged to Allah."
Indonesia for the first time tested its tsunami warning system in Sumatra on Monday — a chilling reminder that the island sits on one of the world's most unstable geological fault lines and is still vulnerable. Scores of powerful aftershocks have rumbled through the region all year.
"We knew it was just a drill," said Candra Yohanes, 55, who was among thousands of residents of Padang town who fled to higher ground when the sirens rang out Monday. "Still, when I heard the siren, my heart was pounding so hard."
At least 216,000 people were killed or disappeared in the waves, The Associated Press found in an assessment of government and credible relief agency figures in each country hit. The U.N. puts the number at least 223,000, though it says some countries are still updating their figures.
The true toll will probably never be known. Many bodies were lost at sea and population data in some places was destroyed.
"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 Monday.
The tsunami generated one of the most generous outpourings of foreign aid ever known. Some $13 billion was pledged to relief and recovery efforts, the U.N. says, of which 75 percent has already been secured.
But the pace of reconstruction has been criticized, and frustration has grown with 80 percent of the 1.8 million people displaced by the waves still living in tents, plywood barracks or with family and friends.
Looking across the part of Banda Aceh that was hardest hit, it seems like little has been done, CBS News Correspondent Barry Petersen reports — houses turned to hulks, fields littered with debris stretched for miles.
There are a lot of people still living the way they were pretty much in the days after the tsunami, some 70,000 are still living in tents. They're
Even in the city of Banda Aceh, where a lot of areas were untouched by the tsunami, the earthquake's ground-ripping upheaval destroyed the city's sewer and water system, Petersen reports.
"Every meter, every yard of pipe in the city of Banda Aceh is ultimately going to have to be replaced. This is the mother of all home improvement projects," aid worker Paul Dillon said.
In Aceh, one survivor dismissively gestured at a jumble of scrap iron and plastic sheeting — all that remains of his neighborhood.
"You want to talk about changes, we've seen nothing," said Baihqi, 24. "Many promises of aid, but that's all we get — promises."
Of the anniversary, he said, "it just means we've existed for one year. We're still around."
The tsunami had the unlikely effect, however, of helping usher peace to the province.
The government and separatist guerillas decided they did not want to add to people's suffering and ended a nearly three-decade civil war that left nearly 15,000 dead.
In Sri Lanka, the waves had the opposite effect. Disputes over tsunami aid and an upsurge in violence have raised fears the island will return to civil war despite a 2002 cease-fire.