"Learning to swim is an essential life skill, and it is great to see that young kids from Port Stephens now have an all year round indoor pool for their learn to swim program," Magnussen said.

Magnussen, who hails from Port Macquarie, did all his learn to swim and junior swimming with Nelson Bay Swim School co-owner Michael Mullens.

"James is a strong advocate for water safety and it is great to see him give back to the sport," Mullens said.

"James and every other Olympic swimmer have the same thing in common with kids enrolled at the swim school - they had to learn how to swim."

In addition to opening the facility, Magnussen talked about the importance of learning to swim and signed autographs for visitors.

Swimmers from the Nelson Bay Swimming Club also got their chance to compete against the 2011 and 2013 100-metre freestyle world champion in a friendly game of handball.

"James was great, he spent all day chatting to people and survived the handball challenge," said Mark O'Malley, another of the swim school owners.

In just a few weeks Nelson Bay Swim School has enrolled more than 250 children in the learn to swim program. Baby classes start at five months of age and progress through the school age years and adults.

"Our swimming lessons will give the kids the swimming skills that could one day save their lives, and hopefully we can create Nelson Bay's next James Magnussen along the way," O'Malley said.

The new centre is also available for 'open swim' sessions from 1-2.30pm each Tuesday and Thursday for people wishing to do their own hydrotherapy and gentle exercise.