Australian man Jonathan Jordan Young has been named as the victim of a water-related incident at Lake Wakatipu in Otago, following the death of another man there less than a week earlier.

Young, of New South Wales, was visiting New Zealand with his fiancée when she watched a rescue attempt from the shore of the lake at Glenorchy last Thursday.

His parents and brother had flown in from Australia to support the fiancée, Otago Lakes central area commander Inspector Paula Enoka said.

A police spokesman said officers and ambulance crew were notified a person was in trouble in the water at the head of the lake, near a reserve, about 4pm on Thursday.

A search was launched with the help of LandSAR volunteers, boaties, a helicopter and other swimmers.

A jet boat involved in the search for Jonathan Young in Lake Wakatipu. Photo / Rhyva van Onselen

Divers were called in, operating from a Dart River Adventures jet boat.

Flowers had been placed at the lakefront, ahead of three new signs put up by the Queenstown Lakes District Council in the morning.

The signs warn of multiple lake hazards, including a steep drop-off close to shore, a strong undertow and unstable footing.

• Man's body found in Lake Wakatipu
• Man found dead in Lake Wakatipu after attempted rescue

Young was helping a child who was in the water when he got into trouble himself, police said, similar circumstances to a death at the same spot.

Less than a week earlier, 48-year-old Leeroy Kaaho, also known as Linkin Kisling, of Wanaka, died last Friday after going in to help his 10-year-old son, who survived.

A Queenstown Lakes District Council spokesman said it would continue working with its partner agencies to consider all measures, including life rings and other flotation devices, which might stop similar incidents from happening again.

Same spot where father died

Witnesses said the events of yesterday afternoon mirrored what happened last Friday.

Jonathan Young was one of three people who went to the aid of a child after they got into difficulty close to the mouth of the Rees River.

The child and the two other rescuers made it back to shore.

The child had been with a family playing on a long sandbank that runs next to the river.

The witnesses believed the three rescuers, a woman and two men, were “Good Samaritans” and not related to the child in distress.

Leroy Kaaho, also known as Linkin Kisling, died while trying to rescue his son in Lake Wakatipu. Photo / Supplied

Witnessing the events was “sad to watch”, one witness said.

A Glenorchy resident said members of the small settlement had discussed the need for an official sign to warn the public since last week’s death, although no action had been taken yet.

The area near the wharf had a steep drop-off, at a nearly 45-degree angle going down to a 21m drop.

Eddies at the mouth of the Rees River made the area north of the wharf “treacherous”, as they could pull unsuspecting swimmers out.