Extinction Rebellion Dunedin co-ordinator Jen Olsen said the group wanted to depict sea level rise "in a fun way".
The event had a serious message, however.
"While people are just carrying on with everyday life, business as usual, climate change is happening around us, and sea level rise is going on."
The protest was part of an international week of action.
There have been more than 400 arrests linked to Extinction Rebellion protests across London as protests there reach their fourth day.
On Tuesday, protesters briefly stopped traffic to a halt at a central Auckland intersection.
Ms Olsen said the London members had "gone to the next level".
The group was relatively new in New Zealand, but wanted to take part in the week of action, and let people know it was active here as well.
The action was timely, considering the Government's just-released Environment Aotearoa 2019 report, which noted polluted waterways in farming areas, the country's myriad species under threat and high per-capita emissions.
Ms Olsen said Extinction Rebellion had begun as a group in Dunedin, and would do whatever necessary to get action on climate change.
More action would be taken in future.
