Inky the octopus escaped from the National Aquarium in Napier.

An octopus at New Zealand's National Aquarium has made a daring escape to the sea by fitting its rugby-ball-sized body through a small pipe.

Staff at the aquarium in Napier noticed the enclosure, which previously housed two octopuses was left with a single inhabitant earlier this year.

Inky, a male common New Zealand octopus, had escaped.

Staff found octopus tracks, which showed he began his journey by slipping through a small gap in the top of his enclosure before travelling across a wet floor.

READ MORE

* Mermaid to create a splash at Napier's National Aquarium

* Same-sex penguin couple raising abandoned chick

* Chick burrows deep in to foster mum's heart

He found a drain, about 150 millimetres in diameter, which led to the sea, and made a dash for freedom.

Rob Yarrall​ from the National Aquarium said Inky was about the size of a rugby ball but octopuses could stretch themselves to extremes, allowing them to squeeze through almost any space.

"As long as it's mouth can fit," Yarrall said.

"Their bodies are squishy but they have a beak, like a parrot."

Since his disappearance aquarium staff have missed Inky, who was popular with staff and visitors, but they were pleased to see him return to the ocean, Yarrall said.

The other octopus was unlikely to miss him as octopuses were solitary creatures that preferred to live alone, he said.

The centre was not actively looking for a new octopus to replace Inky, but if one was to come along they would be happy to accept it, he said.

Inky was given to the centre in 2014 after a fisherman and aquarium volunteer pulled him out of the ocean in a cray pot near Pania Reef, about half a kilometre north of the port of Napier.

He had a few battle scars, which included shortened limbs.

During his time at the aquarium he was entertained with games and toys and he was hand fed fish three times a week.

A couple of months after he arrived the Napier City Council ran a competition to name the octopus, which attracted more than 100 entries.

Gerry Townsend's suggestion "Inky" was the winner as voted by aquarium staff as squirting ink was one of the unique escape mechanisms possessed by octopus.