A fireworks show for Matariki may be postponed if a rare whale continues to swim in the harbour.

The Wellington waterfront has been bustling with excitement as locals try to get a glimpse of the southern right whale.

One man told RNZ he got within 20m of the whale after The Dominion Post Ferry offered those gathered at the waterfront on Thursday morning a free whale watching tour.

"When I grabbed my coffee and just walked back to the waterfront, they announced it and took us out to see the whale - we saw the whale coming up, breathing and diving back in and it showed its fins, it was pretty awesome."

But the presence of the mammal in the harbour has lead to the Wellington City Council to consider postponing the Matariki fireworks event on Saturday. The event, which has been moved from November to align with Matariki - the Māori new year - draws thousands of people to the waterfront every year.

Photo: Maritime NZ/Mark Dittmer

Deputy mayor Jill Day said the council was consulting with experts to see if it should go ahead.

"Our officers are working hard to get all the information they possibly can, so obviously talking to experts who understand the behaviour of these beautiful animals and how a fireworks show would impact on that."

And locals RNZ spoke to are firmly in support of postponing the event if the whale is still in the harbour come Saturday.

"I'd rather see whales than fireworks any day of the week," one man said.

"I think they should definitely, even if they're not entirely sure if he's there or not, it'd be much nicer to think he wasn't going to be disturbed," a woman said.

"If they whale is still here I'd cancel it, protecting the wildlife is more important," another man said.

Department of Conservation marine species support officer Hannah Hendriks said it was the first time in eight years a southern right whale had visited the harbour.

The whale breed was almost hunted into extinction but has since made a comeback, Ms Hendriks said.

She has warned locals to keep their distance from the whale.

"We'd really like people to give it some space so there are the marine mammal regulations that dictate how far you're supposed to stay away from the whale.

"Vessels should be 50m from the whale at all times and only three vessels within 300m," she said.

Police were out patrolling the water on Thursday afternoon to ensure boats and kayakers keep their distance.