The 69-year-old was jumping with Thai Sky Adventures in the resort town of Pattaya, prompting an investigation.
He was named locally as James McConnell, who was originally from Clydebank in Scotland but moved to Thailand almost two decades ago, the Daily Record reported.
Colonel Chonnapat Nawalak, a spokesperson for Nong Kham police, said the cause of his death was not immediately established on Thursday.
“We’re still checking the cause of his death,” he told the Khaosod news website.
“He jumped from the plane and landed in the water, so we have to check whether he died from the jumping or from drowning.”
The centre told the BBC they believed Mr McConnell may have had a heart attack or a stroke after leaving the plane, when witnesses reported the experienced skydiver rolling onto his back and drifting towards the ground.
He missed the designated landing spot at the Thai Sky Adventures base and hit a nearby reservoir.
Harry Harrison, director of the company’s flight operations, said he was pulled out within five minutes by rescuers who attempted to resuscitate him.
It came after a Russian instructor died during a jump at Thai Sky Adventures last year, when a cord attached to his parachute reportedly snapped.
“Our safety record is excellent,” Mr Harrison told the BBC, saying neither death could be attributed to the centre, which has started its own investigation into Mr McConnell’s death.
The company also made international headlines in 2015, when a video emerged showing its plane go into a dive, narrowly missing a par of tandem skydivers, clipping their parachute and narrowly avoiding disaster.
The firm could not immediately be reached by The Independent for comment.
Another British skydiver, David Reader, died in the French Alps after his parachute failed to open last year.
His death came before a 49-year-old woman died after landing in a Durham housing estate when her parachute also failed.
Only licenced skydivers are permitted to jump alone, while less experienced people must do tandem jumps with trained instructors.
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