In his findings released today, Coroner Elliott said Mr Gardner was a strong swimmer who drowned on December 10, 2016.
"Mr Gardner was carrying a child with him as he went out to a pontoon in the river.
"He experienced difficulties when he reached a point where the water became too deep to stand. His ability to remain afloat was made more difficult by the weight of the child he was carrying and by the presence of weeds.
"Although he stayed afloat for long enough for the child to be rescued, Mr Gardner was unable to remain afloat and drowned.''
"It is more probable than not that the additional weight Mr Gardner was carrying made it more difficult to remain afloat.
"He would then have expended more energy than he otherwise would, and this energy would have been expended more quickly. A sense of panic may have also contributed."
Mr Gardner fought to remain afloat until he handed the girl to a relative.
"However, he expended so much energy in doing so that he was unable to keep himself afloat for long enough to be rescued himself."
Coroner Elliott said Mr Gardner's death highlighted the importance of being vigilant about the dangers of swimming, especially in unfamiliar waters.
"The Water Safety New Zealand website advises that natural swimming areas such as rivers and lakes are constantly changing.
"This means that those intending to swim should always check the depth of the water to ensure that they are not swimming beyond their comfort zone or capabilities, especially if bringing children into the water.''
He noted while there was some signage in the area it did not appear that there were any signs about the risks of swimming.
"The presence of the pontoon implied that it was suitable to swim in the area, but there was no signage to remind people of the risks, and no warning that the water was too deep to reach the pontoon on foot or that weeds were growing in the area.
"As I understand it, the relevant area is Crown-owned land which is within the Central Otago District Council region.''
He recommended Crown Property and the council erect signs warning of the water depth, the presence of weeds, the risks associated with swimming in the area and the need to supervise children.
The coroner's findings incorrectly stated the five-year-old girl rescued was Ben Gardner's niece. The story has now been corrected.
