Ehsan Bin Zakaria Muhammad died while swimming with friends in Pinders Pond, a historic sluice pit near Roxburgh, on January 15, 2021.
In her findings released recently, coroner Tracey Fitzgibbon said Mr Bin Zakaria went to the pond with friends about 7pm.
"A friend went to his assistance, but as he reached him, Mr Bin Zakaria sank beneath the water.
"His friend grabbed his hand for a short period of time, but had to let go as he was also being pulled under water."
His friends were unable to find him, and emergency services were called.
His body was recovered by rescue swimmers about 9.30pm.
Ms Fitzgibbon said Mr Bin Zakaria drowned in an area that was two to three metres deep out to a shelf between eight and 10 metres from shore.
Beyond the shelf it dropped away sharply to a maximum depth of 63m.
A postmortem concluded the cause of death to be drowning.
Toxicology testing found THC, the active component of cannabis, in his blood.
"The main effects of cannabis are euphoria and relaxation, an impairment of perception and cognition, and loss of motor co-ordination," she said.
However, there was no evidence to support why he drowned.
"It is possible he misjudged the pond’s depth, or overestimated his swimming abilities.
"However, without additional information, I cannot reach a definitive conclusion."
Mr Bin Zakaria moved to New Zealand in 2017, and completed a degree in accounting from the University of Auckland.
At the time of his death he was working on an orchard in Roxburgh.
His friends said he enjoyed social drinking, and occasionally smoked cannabis.
However, he was fit and athletic, with no significant medical issues.
