Prince William, 42, was left in stitches during a recent conversation with Sir David Attenborough.
The pair sat down to mark World Ocean Day with a candid chat about the broadcaster's long career exploring the planet's seas.
The clip was shared on William's official X account. He described the conversation as: "fascinating to reflect on the wonder of the ocean and the legacy of a man who has dedicated his life to telling its story".
A royal conversation with a twist
© BBCWilliam praised Sir David, 99, for his contribution to nature documentaries. He also asked about the early days of underwater exploration.
The Prince said: "When you first went diving, we knew so little about the underwater world. Is that not fascinating for you to be one of the first people to be able to talk about that and see it?"
Sir David gave a detailed reply. He said: "Oh yes. Once Cousteau invented the Aqua-Lung and the face mask, that was the moment when, suddenly, you moved into a new world.
"You were flying alongside fish, which was an extraordinary experience. And the fish, of course, take no reaction to you, really, because they've never seen anything like you before. The underwater camerapersons are fantastic. They are people who are, I think, happier underwater than they are on land."
William can't stop laughing
© BBCDuring the exchange, Sir David attempted to try on an old-fashioned diving helmet. William reacted quickly and joked: "Don't! You won't be able to get it off David!"
The moment made the Prince burst into laughter. The clip was widely shared and praised for its light-hearted tone.
A deeper message
© BBCThe full conversation is available to watch on YouTube. It highlights both the wonders of the ocean and the urgent environmental threats facing the world today.
William and Sir David also discussed the importance of protecting marine life. They touched on how much the world has learned over the last few decades.
Why World Ocean Day matters
© BBCWorld Ocean Day takes place on 8 June each year. It is recognised by the UN and supported by over 2,000 organisations in 180 countries.
The aim is to promote action to protect the ocean and fight climate change. This year's theme is focused on increasing global efforts to build a sustainable future.
A shared passion for the planet
© BBCWilliam has spoken often about the importance of environmental issues.
His Earthshot Prize is aimed at finding innovative solutions to climate change.
Sir David has been a vocal advocate for the planet for over 60 years.
Their chat was a reminder of their shared mission.
Fans praise the duo
© Getty Images for National GeograThe video was met with a warm response online. Many users enjoyed seeing a more relaxed side of William.
Others praised Sir David for his humour and wisdom. The moment also sparked renewed interest in marine conservation.
