Crossing a swollen river was the biggest contributing factor to the death of a Sydney student in Milford Sound, an inquest has heard.

A coroner's inquest into the death of 22-year-old Yessica Asmin, who died on May 19 last year after she was swept away by icy currents in heavy rain in Fiordland, was held in the Queenstown District Court on Tuesday.

Asmin, an Indonesian studying at the University of NSW, was walking the isolated track with her Sydney boyfriend, Sean Mcnabb, and German backpacker Sebastian Keilholz, who the couple had met just before embarking on the walk.

New Zealand Mountain Safety Council acting operations manager Nathan Watson said an independent review of the incident found the decision and action of the group to cross the "highly dangerous" Pompolona Creek was the most contributing factor to the accident.

"It does not appear the party considered other alternatives (such as returning to shelter) except to cross," Watson said.

The trio should also have used a "mutual support technique" to cross the river, which involved linking arms, instead of crossing the river individually and attempting to help Asmin with walking sticks, Watson said.

Mcnabb and Keilholz both gave evidence that it appeared Asmin panicked after Mcnabb fell into the creek while helping her cross.

Keilholz said he believed she hit her head while being swept away.

Both gave evidence that they were not told nine bridges in the park had been removed because they were prone to avalanche damage in winter, which would mean they would have to do the river crossings.

"It was a bad choice [to cross]. If we were told the bridges were gone, [there would be] no walk," Mcnabb said.

Department of Conservation (DOC) Fiordland district conservation services manager Grant Tremain said there was signage at the visitor centre, where the trio visited the morning before the walk, stating the bridges had been removed, and its website had been updated to let walkers know.

Visitor centre worker Sally Hooke, who spoke with the trio, said her usual conversation with walkers at that time of the year was about track conditions, the absence of the bridges, personal locator beacons and the weather forecast.

Keilholz said he could not remember having a conversation with her.

He said he was told there would be rain and it would be OK.

"They did not say there would be no bridges on the track ... Nobody told us at any stage we would have to cross through water."

TrackNet driver Bruce Fraser said company staff advised the three walkers to change their original plans and to travel straight to the Mintaro Hut, going over the MacKinnon Pass before snow struck.

When asked if they had a location beacon, it became clear none of them knew what a locater beacon was, Fraser said.

After Fraser explained Keilholz's mobile phone would not work in the terrain, and being shown a locater by DOC staffer Daniel Turner at the visitor centre, the trio hired a beacon.

Turner, who said his "general impression" was that the group were underprepared, said he did not talk to them about the bridges being removed but had a conversation with them about how "unenjoyable" the walk would be in the rain.

There was only light rain when Fraser dropped the trio off to embark on the walk.

"I did not feel concerned about their safety," he said.

It was only after they departed that a severe weather warning was issued, forecasting heavy rain in the area.

DOC contractor Adrian Brachysm ran into the trio on the track and said he discussed that there were no bridges with the group and talked about the best place for them to cross the creek.

He had crossed it about 1.30pm and the trio arrived there at 3.30pm.

Asmin's remains were found two days after she was swept away in tree debris in the Clinton River, about 1.8 kilometres south of the last place she was seen.

Since her death, DOC has decided that the bridges would be left up for five weeks longer and has made changes to its website and on the tracks to highlight the hazards visitors face on the Milford, Kepler and Routeburn tracks over winter.

Nearly 22,000 people visited the Milford Track in 2014.

The last death on the Milford Track that was not medical-related was in 1984, when a DOC staff member was killed in an avalanche.

Otago Southland Coroner David Crerar reserved his decision on Asmin's death.

The Southland Times