Police were called to the scene, near the Regional Medical Sciences Center Phuket building, at 8:30am after being notified of the incident by local village chief (Phu Yai Baan) Thawatchai Pinchaisiri.
The man, Yothin Krongkeha, 26, from Loei province, had already been rushed to Thalang Hospital, then transferred to Vachira Phuket Hospital in Phuket Town, reported Thalang Police.
Mr Yothin is in serious condition after he was pulled from the lagoon unconscious and unresponsive, said Capt Nattathee Phichitchainittimaet of the Thalang Police.
At the scene officers found a motorbike parked nearby and a pair of grey rubber sandals, both believed to be those of Mr Yothin.
They also found clumps of “squirrel’s tail seaweed” water reeds, which officers believe Mr Yothin was removing from the lagoon.
An inmate washing a car at a nearby car care saw Mr Yothin in distress and called for help, then rushed to assist him, explained Capt Nattathee.
However, by the time the inmate made it into the water he was unable to find Mr Yothin, he said.
Rescue workers from the Kusoldharm Foundation soon arrived and after a brief search found Mr Yothin and brought him to shore. The rescue workers administered CPR until they could detect that Mr Yothin had at least a weak pulse, then sped him to hospital, he added.
The inmate who saw and responded to Mr Yothin’s situation was praised for this actions.
“He is known to be a good member of the community,” Capt Nattathee said.
The Baan Bangjo facility is an outplacement extension of Phuket Prison where prisoners soon to be released undergo resocialisation before rejoining society.