On Tuesday, health officials announced 98 new cases of the virus, including 74 in Auckland and others in the Waikato, Bay of Plenty, Taranaki and Tasman.

It is the third time in five days cases have been held below 100, after several days above 200 in November.

The Delta variant has reached South Island's Fiordland, courtesy of a walker, or tramper, who spent Saturday night in the picturesque Green Lake Hut.

The region is home to the iconic Milford Track, described as the world's best bushwalk, and a spate of other day and overnight walks.

Green Lake Hut is found 7km, or three hours hiking, inland from the trailhead near Lake Monowai, south of the town of Te Anau.

The Department of Conservation-managed hut has 12 bunk beds, a non-flush toilet and untreated water, and costs $NZ5 ($A4.79) for an adult to spend the night.

COVID-19 Minister Chris Hipkins told AAP "you'd be pretty unlucky" to head off into the lightly populated region only to bunk down with an infectious case.

"It's certainly the remotest location of interest I can think of," he said.

On the same day Green Lake Hut was listed as a location of interest, Southland, the health authority responsible for the region, became New Zealand's fifth to reach 90 per cent of people double-vaccinated.

Southland joins two Auckland-based regions, Wellington and Christchurch in reaching the milestone.

In total, 88 per cent of New Zealanders aged 12 and over have been fully vaccinated, with a further five per cent partially vaccinated.

Hospitalisations are also down, with 66 Kiwis in hospital - down from 76 on Monday. Seven remain in intensive care.

Public health experts expect a growth in cases following the end of Auckland's 107-day lockdown last week.

Australian Associated Press