With the search continuing for the body of one of the dead, Department of Disaster Prevention and Mitigation officer Somkiert Intarakam today ordered six tour companies - who mostly rely on Phuket tourists - to stop operating.
As well as banning whitewater rafting, department officials also ordered the companies to stop elephant trekking because of concerns about deadly landslips.
One 28-year-old Phuket tourist from Kuwait is dead, his body recovered. Missing is an Egyptian man, aged 24. His wife, also aged 24, and a Kuwaiti man, aged 48, were rescued and treated at Phang Nga Hospital yesterday.
It is believed they have since been discharged and allowed to return to Phuket.
With them in a round inflatable raft yesterday were two local guides based at Baan Songprag in Phang Nga, the province north of Phuket. Local village chief Boonrong Jamroonsawatdichai explained today what had happened.
He said that the whitewater operators had suspended operations for two days as Phuket, Phang Nga and the entire region took a pounding from the seasonal southwest monsoons.
When there was a break in the weather yesterday, they decided it was time to resume whitewater rafting.
As the four Phuket tourists and their guides rode downstream, a massive torrent of water roared downstream and capsized the raft, flinging everyone into the water, Khun Boonrong said.
The guides were able to rescue two of the Phuket tourists, but could not save them all.
Khun Boonrong said that on past experience with a case in 2006, when British tourist Shenaz Kapoor, 22, disappeared and drowned, it could take up to 10 days to find the lost man.
In 2005 Australian Rachel O'Neill, 29, drowned when she fell out of a raft and was trapped underwater by rocks.
The whitewater rafting season north of Phuket usually begins with the arrival of the southwest monsoon and continues through until November.
Unusually large amounts of rain have fallen over the Phuket region this week, especially on Thursday when a powerful storm battered Phuket's holiday west coast beaches and flooded much of Patong and Phuket City, toppling trees into powerlines and triggering traffic chaos.
Phuket and Phang Nga remain among eight provinces listed today at being at risk of flooding and landslips, although the sunshine returned in Phuket City this morning and tourists returned to the beaches in greater numbers.