The vast majority are Muslim Rohingya, fleeing persecution and ethnic cleansing inside Burma, with hatred at their backs.
At least 10,000 people have taken to boats in the past three months. The tranquil Andaman Sea ''sailing season'' extends for six months and is only half over, so thousands more will join them.
While the numbers are huge and growing every day, Burma and its neighbors inside and outside the Asean group appear to be ignoring or downplaying this historic exodus.
Voyaging past Phuket and the surrounding Thai holiday coast, people smugglers mostly pay off officials and deposit their human cargoes close to the Thai-Malaysia border, which is usually crossed covertly on the mainland.
Today's news that hundreds of people from Burma - probably Rohingya - have been forced to swim from a vessel offshore to the Malaysian holiday island of Langkawi comes as a surprise.
Mainstream media reports about the Rohingya and their fate at sea have been rare in Thailand and Malaysia since so-called communal violence ripped Burma's Rakhine state in June.
Unconfirmed reports say one man drowned and two others remain in critical condition after more than 400 people were forced to swim ashore in Langkawi.
The incident follows a standoff earlier this month in which a Vietnamese cargo boat, carrying 40 Rohingya rescued from a sinking in which about 200 others died, was refused permission to dock in Singapore.
One newspaper report says that on Langkawi, about 50 passengers from the vessel may have also fled into the surrounding scrub to escape detention.
Chris Lewa is director of the activist group Arakan Project, which compiles statistics based on the departure of Rohingya from the Burma-Bangladesh border.
''We have recorded 1700 people leaving in October, 3800 in November and 5000 in December,'' she said.
''There could be many more leaving from further south, around Sittwe. We just don't know.''
NGOs and the media are not encouraged to visit the mass displaced persons camps for thousands of Rohingya around Sittwe.
Hundreds more Rohingya have departed since June, when the troubles began, unprepared to wait for smoother ''sailing season'' seas.
At least five sinkings of vessels have been recorded since then, Ms Lewa said, with up to 200 drownings in the worst catastrophe.
Rohingya have been sailing fishing boats south for years but now larger vessels are also being used, she said.
''The Rohingya are ferried out to the larger vessels,'' she said. ''We have two accounts recently of vessels carrying 700 people each sailing south.''
Arakan Project records showed 33 boats leaving the northern region over a four-week period.
She said the vessel now off Langkawi departed from South Maungdaw on December 19.
''The number is huge,'' she said. ''There are so many arriving in Malaysia now.''
It's possible that the Rohingya dropped offshore in Langkawi were from a large cargo vessel of the kind that more often deposits passengers off the southern coast of Thailand.
A group of 127 Rohingya, arrested recently in southern Thailand motoring in a convoy of five minivans towards the Malaysian border, may well have come off one of the larger cargo vessels.
Publicly, Thailand's policy is to ''help on'' Rohingya boats by supplying them with food, water and fuel if they are apprehended in coastal waters.
Mistreatment of the Rohingya and the lack of action by Asean has been one of the region's biggest issues since Phuketwan and the South China Morning Post newspaper revealed the secret pushbacks from Thailand that led to several hundred deaths in the 2008-2009 sailing season.