There are 15 new coronavirus cases today as Prime Minister Jacinda Ardern reveals what life will look like on the other side of lockdown.

When New Zealand moves to alert level 3, there would be a partial opening of schools for students up to Year 10 only and attendance isn't mandatory, Ardern said.

Students who can remain home and do distance learning are encouraged to do so.

Children at school would be kept in the same groups each day and it would be down to each school to work out how to do that, Ardern said.

Public play equipment would remain closed.

Public-facing bars and cafes, malls and retail stores have too much contact with the public so they will remain closed.

But food deliveries and e-commerce could re-open, she said.

Drive-through services at restaurants are also allowed.

The hospitality won't be able to have face-to-face interactions so restaurants would need to rely on deliveries and retailers have to utilise click and collect.

There could be takeaway coffees, as long as it could be done through an app or online.

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Travel restrictions will remain under alert level 3.

But the advice has changed from "keep it local" to "keep it regional" and travel should be restricted as much as possible.

Ardern said the different Covid-19 levels allow different levels of contact between people.

Level 3 is about "restrict" as there was a risk the virus could "bounce back", she said.

Boating and jetskis are still banned because they can be prone to breakdown.

But you can swim, surf and fish from the shore.

Don't start a new activity that you haven't done before, the PM said.

If there are signs of congregation, this rule will be reconsidered so Kiwis shouldn't consider it a time to catch-up with all their swimming buddies, Ardern said.

People should keep their bubble at level 3 but can expand it "a small amount", she said.

Those who need carers, have shared custody, or want to see their family could do so.

"Keep it exclusive, keep it small," she said.

For bubbles which included older people or with pre-existing conditions, those people should still be kept safe.

"People need to really use their judgment," Director General of Health Ashley Bloomfield said.

If there was a child in that bubble, it would be advised to keep the child home from school if possible.

Even though the bubbles were being slightly expanded, Kiwis should try to keep them as limited as possible.

If you are able to work from home, you must, Ardern said.

But if that is impossible to do so, for example if you work as a plumber, you can do so but you have to maintain social distancing.

MBIE advised the Government the numbers of people who could work under level 3 doubled from level 4, Ardern said.

Funerals and tangi can go ahead but only 10 people can attend.

Weddings are also restricted to 10 people and only services can take place - there can't be any meals or receptions.

One metre is the new distance you should keep to but you have to be able to contact-trace.

Keep a note of where you've been, when and who you saw, she said.

Why NZ still has restrictions

Ardern said there were still restrictions because the end goal was elimination. "When we get there, we want to stay there."

New Zealand will need a team of five million to achieve the goal of elimination, she said.

On the voluntary return to schools, Ardern said that was because other parents would be returning to the workforce instead of just essential workers.

The reason for allowing up to and including Year 10 covered children under 14 who legally couldn't stay home alone so parents returning to work could have childcare.

Lockdown was easier to enforce as it was "black and white" and so at alert level 3, that would be harder to police.

Ardern said she was relying on New Zealanders to be responsible.

Businesses wanting to trade are expected to put hygiene and social distancing measures in place and more details about MBIE's accreditation scheme would be released next week.

On whether some regions would come out of level 4 before others, Ardern said they would factor in whether that was workable as there were concerns about that.

Kiwis shouldn't push "to the maximum" of how far they could go and should stay within their regions.

About the West Coast and whether it could be lifted out soon, Ardern said no decision had been made about any part of the country coming out of lockdown.

Ardern once again referred to level 3 as a waiting room and said this was because "we have to wait and see if what we've done has worked".

Ardern told reporters that the indications of the actions taken against Covid-19 were "promising".

"We should not confuse the success of our actions with overreaction," the PM said.

The actions were about protecting people's livelihoods as well as fighting the virus, she said.

Ardern said revealing the alert level rules "in no way" foreshadows whether the lockdown will be lifted next week, Ardern said.

She said the last thing the Government wanted was to "give away" the gains New Zealand had made under the lockdown.

15 new cases today

Bloomfield says the 15 new cases are made up of six confirmed cases and nine probable cases.

Twelve people are in hospital, three are in ICU and two are in a critical condition.

Four per cent of cases now classified as "under investigation" and 23 cases since March 24 are in that category.

Five of those cases are due to overseas exposure and 13 are connected to known cases.

Four are now classified as "community-acquired" and one case from yesterday is still under investigation

This detailed information on the sources of infection will form part of the decision to lift the country out of lockdown, Bloomfield said.

Eighty-eight people who arrived from overseas remain in quarantine.

Three hundred people at a supermarket in Queenstown are being swabbed today for sentinel testing.

There are no new significant clusters, so the total stands at 16.

A post-mortem is underway for the man who died in Invercargill thought to be coronavirus-related, Bloomfield said.

The Invercargill case was connected to the Bluff wedding cluster, he said.

Bloomfield said it's still not 100 per cent certain where the infection case came from at the Rosewood rest home.