An octopus made a dash for freedom from its enclosure by squeezing through pipes that led out to sea, staff at an aquarium said.
Inky the Octopus, a resident at New Zealand's national aquarium for two years, made his great escape in the middle of the night after the lid of his tank was left ajar.
He then squeezed his rugby ball-sized body through a 150mm-wide pipe that ran under the aquarium for 50 metres and to get out to sea.
The male common New Zealand octopus has not been seen since and is assumed to be living a life of freedom in the wild.
Staff at the aquarium worked out plucky Inky's route after they found octopus tracks from his tank and across the wet floor leading to the drain pipes.
Despite being the size of a rugby ball, octopuses can stretch themselves to extremes and squeeze through almost any space, Rob Yarrall from the National Aquarium said.
"As long as it's mouth can fit," he added. "Their bodies are squishy but they have a beak, like a parrot."
Staff mapped out his escape route in the three images below:
Inky was popular with staff and visitors, Yarrall said, but they were pleased that he has returned to the ocean.
Another octopus, who shared a tank with Inky, had not made a break for freedom and as they are solitary creatures is unlikely to pine for him, he added.
Inky was given to the aquarium in 2014 by a fisherman after he was pulled out of the ocean in a cray pot near Pania Reef, north of the port of Napier.
He had some injuries including shortened limbs.
Shortly after his arrival, a competition was held to name him which attracted more than 100 entries.
The winning suggestion Inky, by Gerry Townsend, was chosen as it referred to the unique escape mechanism possessed by octopuses.