Giant tanker docks at Wellington 

A Behemoth that could power half the cars on New Zealand roads docked in Wellington Harbour on Friday.

It's the largest oil tanker to come to New Zealand, bringing petrol from Lithuania.

Diana Stretch from BP says the government may have ditched its eight cent a litre petrol charge this week but there is still a cost that comes with being green.

"Our stringent fuel specifications mean there's only a handful of distant places on the planet we can import it from," says Stretch.

The eye-popping fuel tanker is carrying a $90 million cargo. The fuel is low sulphur petrol, which is considered good oil, and that meant importing it all the way from Lithuania.

"The kind of recipe that makes up petrol for New Zealand is quite unique and we're having trouble sourcing that, our refinery in New Zealand can only make about half of our petrol needs so we've had to go further and further away," says Stretch.

The 229-metre, 100 million litre ship set out from Eastern Europe two months ago.

The Torm Venture has already offloaded 20 million litres of fuel in Mount Manganui and it will offload another 27 million in Wellington on Friday.

But it was not the only nautical novelty on the Wellington harbour.

A 250-metre long floating refinery was also making a stopover at the Wellington Harbour, before joining the platform in the Maari oilfield, off the coast of Taranaki - a field expected to produce 50 million barrels of oil in the next 15 years.

Stretch says New Zealand will see a lot more of really huge tankers on our shores over the next few years.

"...we struggle to source the product that we need for New Zealand because of the specifications," says Stretch.

It is an expensive process and with the government taxing every litre leaving the ship - that's about $14 million on Friday alone - at the petrol pumps for the average kiwi, the prices will keep stinging for a lot longer.