DIVE IN: Emperor penguin Happy Feet slides off the back of the Tangaroa and into the Southern Ocean.

SLIP'N SLIDE: Emperor penguin Happy Feet is released into the Southern Ocean.

TUXEDO READY: Emperor penguin Happy Feet just before being released into the Southern Ocean.

KING FOR A DAY: Emperor penguin Happy Feet at the top of the Tangaroa's ramp before being released into the Southern Ocean.

RULING CLASS: Emperor penguin Happy Feet just before being released into the Southern Ocean.

Two months after he washed up on a beach north of Wellington, Happy Feet has been released into the Southern Ocean.

The emperor penguin was freed earlier this morning just north of Campbell Island, from the stern ramp of the research vessel Tangaroa.

The boat left Wellington on Monday, with Happy Feet housed in a specially-designed crate filled with ice.

NIWA DIVE IN: Emperor penguin Happy Feet slides off the back of the Tangaroa and into the Southern Ocean.

The journey south was hampered by rough conditions, but overnight the Tangaroa finally made it to the drop-off latitude of 51 degrees.

Sea conditions were too rough to release Happy Feet by hand, so he was released down a tarpaulin 'hydro-slide' from the boat's ramp.

Wellington Zoo vet Lisa Argilla, who has been looking after the penguin onboard, said he needed some "gentle encouragement" to leave his crate but the release had gone well.

"He slid down his specially designed penguin slide backwards but once he hit the water he spared no time in diving off away from the boat and all those 'aliens' who have been looking after him for so long."

The National Institute of Water and Atmospheric Research team and boat crew were all on deck to say goodbye, she said.

"It's an indescribable feeling to see a patient finally set free!"

Voyage leader Richard O'Driscoll said apart from a few nips at feeding time, Happy Feet had been a well-behaved passenger.

"It's been a pleasure to have Happy Feet onboard.

"We are just happy to help him on his journey home."

Prime Minister John Key was today clearly delighted Happy Feet got away.

"I am glad an orca whale didn't eat him; we wish him the best."

Happy Feet has been fitted with a tracking device so the team and public can follow his progress back home.

The wayward penguin was found on Peka Peka beach in late June, exhausted and hungry after journeying 1000km north of his normal habitat.

He was treated at the zoo after swallowing large amounts of sand.

The Tangaroa research team will now continue its month-long survey of southern blue whiting stocks.