Jonathan Jordan Young, 35, and Leroy Rodney James Kaaho, 48, both dived in to save children near the top of Lake Wakatipu in January 2023 but did not survive.
Coroner Meenal Duggal's findings into the men's deaths have now been released.
On January 13, Kaaho (also known as Linkin Romeo Jewels Kisling) visited the spot with his family. Two of his children, Tama and Memphis, went for a swim in the Rees River, which leads into Lake Wakatipu.
The coroner's report said the boys began floating on their backs and drifted quickly down the Rees River.
Memphis was able to swim back to shore but Tama continued to struggle and drift further out into Lake Wakatipu.
Kaaho went into the lake to retrieve Tama, who was 20 metres from the shoreline, but got into difficulty a few metres away from him and began yelling for help.
A witness ran into the lake and swam out to Tama, and saw Kaaho's head submerged under the water.
The witness managed to bring Tama back to the shore. He was conscious and placed in the recovery position until emergency services arrived.
Helicopters and boats searched for Kaaho, and his body was found during a police dive squad search the next day, at a depth of 24m.
Less than a week later, on January 19, Young visited the spot with his fiancée, Hsu Lae Tin. He was visiting New Zealand from New South Wales in Australia.
The coroner's report said Young swam out to help a young boy who got into difficulty while playing in the Rees River and started drifting out.
The boy was about 10m from the shore when Young reached him. However, after pulling him for a few metres they got into difficulty and drifted apart. Another member of the public entered the water to help.
Young remained in the water and was about five to seven metres from shore when he stopped swimming. Witnesses stated he was floating on his back but did not look in distress.
His fiancé screamed his name and encouraged him to keep swimming. She saw his head bobbing up and down before he disappeared, completely submerged under the water.
A search was undertaken by nearby boats, police and the Westpac rescue helicopter without success.
The police dive squad found Young's body the next day at a depth of 15m.
Duggal's reports said both Young and Kaaho were reported to be good swimmers.
More work needed
After the deaths, Queenstown Lakes District Council put up multiple new signs at Lake Wakatipu, warning the public not to swim in the lake, of the dangers of swimming near a river mouth, and of hazards in the lake such as the steep drop off, strong undertow, and unstable footing on the lake-bed.
Life rings have been installed on the jetty and the mouth of the Rees River, and the council was in the process of building a rope structure which would outline the preferred swimming area.
Duggal said these were positive steps, but more work was needed to protect visitors.
"Water Safety New Zealand currently reports that more people drown in rivers than in any other aquatic environment. Considering that there have been two drownings of similar circumstances in one week at Lake Wakatipu and Rees River, I am of the view that further efforts need to be made to ensure the safety of the public in this area."
Duggal encouraged the council to continue raising awareness and educating the public on the risks and hazards present in its lakes and rivers, particularly Lake Wakatipu.
"These campaigns should be easily accessible for tourists or non-locals, who may not be aware of the dangers associated with New Zealand's rivers and lakes."
