Aid has begun to reach thousands of quake survivors in Indonesian villages a week after tidal waves washed away entire towns around the Indian Ocean.
But despite the $2 billion in aid pledged so far, the UN said on Sunday that it could take two weeks just to reach some people and predicted the final toll, now at almost 130,000, would rise to 150,000.
The new year brought a surge of cash pledges. Japan vowed half a billion dollars to help and Washington raised its contribution tenfold to $350 million.
The aid drive is vast but cannot be big enough. UN health officials say disease is set to kill up to 50,000 more people.
Danish Red Cross chief Jorgen Poulsen, in the devastated city of Banda Aceh on Sumatra's northern tip, said waterborne diseases such as dysentery were "a ticking time bomb".
"We hope we can avoid cholera. The problem is we have already seen people vomiting in town," he said.
Forty countries lost nationals in addition to the 13 countries hit directly by the tsunami.
Indonesia lost over 80,000 people, Sri Lanka nearly 30,000, India 12,700 and the 5,000 killed in Thailand included many tourists, mainly European.
Water is only just beginning to drain out of parts of Banda Aceh, revealing the full extent of the damage and yet more bodies to count in a nightmarish landscape.
"I've never seen anything like this. We've seen bodies 20 miles out to sea. You just cannot describe it"
Captain Larry Burt,
"I've never seen anything like this. We've seen bodies 20 miles out to sea. You just cannot describe it," said Captain Larry Burt, commander of a helicopter air wing on the carrier USS Abraham Lincoln, anchored off the Sumatra coast.
Walking the streets of Banda Aceh on Sunday, clean-up crews and exhausted soldiers found it hard to know where to start. Hundreds of decomposing bodies lay in the streets. Fires burned around the clock to clear streets of wooden debris.
World Vision Australia chief Tim Costello, who visited devastated areas of Sri Lanka, said the scenes he had witnessed were like "the apocalypse".
"This is the face of utter, utter human suffering," he said on his return to Australia. "I saw things I wish I had never seen and I certainly wish no humans should ever, ever have suffered.
"Everywhere on that coastline people are suffering. People are desperate and begging for food, begging for water."
In India, where 13,000 have died, officials said another 5400 people were missing across the remote Andaman and Nicobar islands. Aid workers said the toll could be much higher because they had been unable to reach the interior of many islands.
Rescue workers are using small rubber and wooden boats to reach islands where roads are impassable.