Harry and Meghan had a go at waxing a surfboard as they dipped their toes in the sand at Bondi Beach.
The parents-to-be met surfers from the OneWave group at the famous Sydney beach to discuss mental health issues.
Harry was offered the chance to don a wet suit and grab a board, but time was not on their side.
The couple travelled to the beach on their 16-day tour to take part in Fluro Friday, where people dress up in fluorescent clothes and go to the beach, with the aim of fostering an atmosphere where others can open up about their own mental health issues.
To turn the tide on stigma surrounding mental health issues, OneWave is encouraging people to share their experiences of living with mental health issues and the power of opening up using #OneRoyalFluroWave#RoyalVisitAustraliapic.twitter.com/YGvk8vmptC
— Kensington Palace (@KensingtonRoyal) October 18, 2018
It was founded by Grant Trebilco, who suffered from mental health issues for a decade but felt unable to talk about them.
He was eventually diagnosed with bipolar disorder and was hospitalised.
During their visit to the beach, the couple walked barefoot to sit in a group with some of the brightly-dressed surfers.
Harry and Meghan spent about 10 minutes listening to the experiences of other members of the group and sharing their own.
Dabriella Quayle, 37, said afterwards: “Oh my goodness, they were just so real, so relatable. They shared their own experiences, which was amazing.
“Harry said seeking help was the best thing he had ever done. He was really open and honest. He said it doesn’t matter who you open up to, they don’t have to be professional.
“Anyone can be there for you. It could be your best mate or a stranger. You just need to open up to them.”
Harry and Meghan were both given the chance to wax a board after the duke said he had never done it.
Surf instructor Sam Schumacher, 31, said the couple both said they had surfed before, adding: “This visit will really raise the profile of what we are trying to do and the fact that mental health doesn’t discriminate.
“It can affect anyone and that we all need to try and look after each other. I can see the passion in their eyes.”
— Alexander Britton (@adbritton) October 18, 2018
Mr Trebilco said the couple were “engaging” and “had time for everyone”.
He added: “We tried to get him in and told him we had a wet suit and surf board ready for him, but he said he couldn’t.
“They were so engaging, they had time for everyone and really felt part of the One Wave community.”