The 3.3km ocean swim started at Frank Kitts Park just before 9.30am and continued out to the Point Jerningham Lighthouse and finishing at Freyberg Beach in Oriental Bay.

More than 1000 swimmers of different ages and stages in life took the plunge in Wellington Harbour as part of the Interislander Capital Classic.

The Banana Boat New Zealand Ocean Swim series, held across the country over summer, encourages kiwis to set themselves a swimming goal and get into the ocean.

Amongst those eager to take advantage of the warm weather and test their fitness in Wellington on Sunday were John Marshall, 82, and Cadence McHugo, 12.

SUPPLIED John Marshall, 82, and Cadence McHugo, 12, were the oldest and youngest participants in the Capital Classic Ocean Swim at Oriental Bay on Sunday.

Though 70-odd years separates them, the oldest and youngest competitors in the 3.3km race said the same thing motivated them – a chance to push themselves and have fun.

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The ocean swim started at Frank Kitts Park just before 9.30am and continued out to the Point Jerningham Lighthouse before finishing at Freyberg Beach in Oriental Bay.

SUPPLIED Swimmers of all ages are encouraged to participate in the Ocean Swim classic.

Cadence, from Manakau, near Ōtaki, is a keen swimmer and member of the Ōtaki Surf Lifesaving Club who was taking part in the full swim for the first time.

"I just wanted to push myself and see what I could do."

Staying steady and in a straight line during the 2km swim to the lighthouse was the most difficult part of the race, she said.

Supplied Competitors gather under a blue sky at Fank Kitts Park ahead of the Interislander Capital Classic on Sunday.

It was also "a little bit cold and there were lots of jellyfish", but Marshall provided her with some valuable advice before the race.

"He said just relax and the start and don't go too fast," Cadence said.