Joshua Paroci (31), of Sydney, drowned in the "toilet" rapids in Skippers Canyon on May 19, 2018, during a trip to Queenstown with five friends.
In her findings released today, coroner Heather McKenzie said Mr Paroci’s group was on one of three rafts on the Queenstown Rafting trip when it flipped over.
Although his five friends were retrieved, Mr Paroci began experiencing difficulty after a safety rope was thrown to him.
As he was pulled to the river bank, he let go of the rope about a metre from safety and floated downstream.
A guide in a safety kayak went to his assistance, and although Mr Paroci was initially able to hold on to the kayak’s hand grips, he again let go.
Attempts to revive him with CPR and a defibrillator continued for 45 minutes until the arrival of the first of two rescue helicopters about 5pm, but paramedics declared him dead about 10 minutes later.
Following a postmortem, a pathologist found the cause of death to be drowning, but noted the presence of a hypertension and angina medication in his blood.
That prompted a second opinion to be sought from another pathologist, who concluded it was "possible but not probable" the cause of death was cardiac disease, or impairment by cardiac disease leading to drowning.
A report by Mr Paroci’s GP said he had been treated for hypertension since 2014, had "longstanding obesity" and a family history of heart disease, hypertension and high cholesterol.
One of the pathologists said Mr Paroci’s 124kg weight meant the prolonged effort needed to maintain a grip on the rope and kayak while in strong rapids would have been "probably very considerable indeed".
The effects of cold hands, inhaling water and a potential cardiac event were other possible contributing factors.
An investigation by Maritime New Zealand concluded Queenstown Rafting worked to "very high standards" in its industry, and its guides had followed correct procedures from when the raft flipped until the helicopter paramedics arrived.
Ms McKenzie said multiple safety briefings were given before and during the trip, and participants had to declare any medical conditions or medications on a waiver form.
"The nature of the trip is that it is an adventure activity which is very physical, especially when passing through serious rapids and then if a client comes out of the raft into the river."
Mr Paroci’s death was an accident, and no party was to blame, she said.
She did not consider any recommendations to be appropriate, noting Queenstown Rafting had made changes to its operations since the tragedy, including filming its trips with GoPro cameras, installing extra safety lines in rapid areas and limiting the weight of clients to 120kg.
