At the age of just 16, he rushed into the ocean with his surfboard at Denhams Beach near Batemans Bay, threw a small child on his back and pulled a drowning father up out of the water before assisting both victims to shore.

His timely intervention prevented a certain tragedy and has resulted in a Commendation for Brave Conduct, the sole Canberra citizen to be honoured in the Governor-General's awards this year.

It has been well over two years since that Canberra Day incident in 2017 and when the email advising him of the award arrived in his inbox recently, William, now 19 and from Conder, was flabbergasted.

"For me, it's a day I won't forget but it's been so long since then that I thought it was all said and done," he said.

"So this [honour] was unexpected and quite a surprise."

He was a year 11 student at Erindale College and leaving the beach with his family when he saw the family in trouble in the water, rushed down to the water's edge with his surfboard, and grabbed another board off the beach.

Without hesitation he paddled out to save Canberra man Anuar Medina and his three young children, Freja, Francis and Francesca, all of whom had been snatched by the pounding shorebreak, dragged into the ocean and were trapped in a fast-moving rip.

"I think the thing that always sticks with me is how fast the family got into trouble and how quick that rip was running; in seconds they were sucked 20 metres out off the beach and heading out to sea," William recalled.

William had grown up near the beach and as an experienced surfer had often used a beach rip as a fast-track ocean travelator to get "out the back" to where the waves are breaking.

"The swell had risen a lot from when we had gone surfing earlier in the day and conditions were pretty gnarly and choppy," he said.

Two of the children had drifted closer to the rocks so William gave them the borrowed surfboard for flotation, told them to "hang on", and headed further out to where Mr Medina was seconds from drowning.

"Anuar was going under and his daughter was frantic so I grabbed her first and put her on my back, then grabbed his arms and pulled him up from under the water; he was semi-conscious, in a pretty bad way and had swallowed a lot of water," William said.

"My Dad [Kevin] then turned up on his board and between us we were able to support him [Mr Medina] and swim him out of the rip and get him back to shore."

Mr Medina was taken by ambulance to hospital and treated but fully recovered. All the children were unharmed.

William, now at university and studying to be a teacher, said that while he was flattered by the recognition and the national award, his overriding desire was that it would demonstrate how important it was to teach more people about ocean safety.

"I'm really lucky because I've grown up with the ocean and going surfing a lot with my Dad," he said.

"But that incident made me realise that so many people don't know what to do when they are caught in a rip because they try to swim against it and get exhausted.

"If we educated everyone about ocean safety at a young age, I'm sure many lives would be saved."