Thailand's authorities have said more than 700 bodies have been retrieved from Khao Lak resort near the island of Phuket following Sunday's sea surges.
Khao Lak may have been the worst hit area in Thailand
Many of the bodies have been pulled out from rooms of the Sofitel hotel, popular with French tourists.
The area is strewn with corpses which overwhelmed relief workers are trying to remove, a survivor told the BBC.
Thailand's official death toll now stands at 1,516 after the 9.0 magnitude undersea earthquake.
Dutch-born Maurice de Jong, who lives in Phuket, told the BBC News website: "There are bodies everywhere, just lying in fields, to the left and right of you.
"The bodies are smelling very bad. They are struggling to get all of them onto pick-up trucks."
A correspondent for France's Europe 1 radio reported that only a few walls of the Sofitel still remained standing and that soldiers were still pulling out people from the hotel's 319 rooms.
Deputy Interior Minister Sutham Saengpratoom estimated he had seen more than 1,000 bodies on the
beach in the area when he flew over it on Monday.
That number would make it the most severely hit resort in Thailand.
As well as the dead, many children have also been separated from their parents.
A Swedish man said he had been reunited with his two-year-old nephew after reading on the internet that the boy had been found and taken to a hospital.
The fate of the parents is still unclear.
Bejkhajorn Saithong, 39, told Reuters news agency he was searching for the body of his wife at the Ban Khao Lak Hotel, where body parts are jutting from the wreckage.
"My son is crying for his mother. I think this is her. I recognise her hand, but I'm not sure," he said.
A police patrol boat was reported to be stuck in a tree 1km from the shore.
Chantima Saengli, the owner of the devastated Blue Village Pagarang hotel, told local radio she feared 340 of her 400 Scandinavian guests were dead.
The island of Phi Phi, famous as the location of the film The Beach, is also reported to have been devastated.
At least 200 tourists and islanders were airlifted from the island by helicopter on Monday, but scores more are still missing.
A photographer with the AFP news agency, who reached the island on Monday, said hardly a building had been left standing.
"I see one building standing and it is the Phi Phi hotel," he said.
Tourism is one of Thailand's most important industries, with hundreds of thousands of tourists drawn to its beaches each year.
In neighbouring Malaysia, at least 50 people were reported killed after the tidal waves hit. Most of the dead were in the holiday resort of Penang.