By Agence France-Presse
The Phoenix was carrying around 90 passengers when it began to keel over after it was hit by massive waves, prompting a rescue operation that stretched into the night and left authorities scrambling to react.
The body of a man wearing a life jacket with the logo of the Phoenix boat was pulled from the sea late Thursday.
Footage shown live on the public relations Facebook page of Phuket showed the body being brought to shore. The victim was found near one of a string of islands off Phuket's coast.
"There are 53 people missing," the governor of southern Phuket, Noraphat Plodthong told reporters. "We have stopped the rescue... we'll start again in the morning."
Thailand has a sketchy health and safety record and accidents are common on its roads and busy waterways -- especially during the monsoon season which is now biting.
The kingdom is already in the global spotlight for a dramatic rescue mission in the north of the country, after 12 boys and their football coach were trapped in a cave complex.
Television footage taken at a pier in Phuket showed stunned tourists huddling in blankets, while several women cried as medics tended to the injured.
The boat was returning to Phuket from Koh Racha at around 4:00 pm (0900 GMT) when a storm hit, according to the captain, who identified himself as Somjing Boontham in a televised interview.
He said the boat was hit by five metre-high waves, which flooded the boat that started to slowly keel over, prompting him to warn passengers to put on life jackets and trigger inflatable life rafts.
"So I sent someone to them to wear life jackets... They were all Chinese visitors -- apart from two farang," he said using Thai vernacular for Westerners, adding around half the passengers were unaccounted for.
Phuket is a magnet for overseas visitors including Western sun-seekers and huge numbers of Chinese tourists who make up the bulk of the 35 million people expected to visit the kingdom this year.
Governor Noraphat said Phuket officials had issued a weather warning on Wednesday alerting the public about impending storms.
"There were high winds this evening," he said, adding a further 10 pleasure boats were stranded at sea and being attended to by rescue vessels from the police and navy.
Two other separate boat capsizes were reported in the same area Thursday evening.
A yacht called the Senerita carrying 39 people also capsized in the high seas, the officials added.
All of the passengers in both cases were pulled from the sea alive.
Photographs circulating on social media showed soaked and exhausted passengers -- most of them Asian -- in life jackets being pulled on inflatable rafts to safety.
It was not immediately clear which boat they belonged to.
China's state-run Xinhua news agency said its consulate in the southern Thai city of Songkhla had been informed by local authorities that two vessels with Chinese nationals on board had capsized and that efforts were under way to rescue them.
"There are some Chinese tourists on board," Xinhua reported the consulate-general as saying. "They are mostly one-day individual visitors (day trippers) or staff and their families of a Chinese company."
The report, which did not name either of the vessels, said that "the majority of 133 passengers on two boats overturned by rough seas in southern Thailand were saved."
However, it was based on information received by the consulate at 8.30 pm (1330 GMT), some three hours before Thai officials later confirmed some 53 people were missing and that the search had been called off until morning.