The Sussexes' son Archie is a massive fan of the children's cartoon Octonauts with its underwater adventures, said a pal of Prince Harry.
Archie, aged three, loves to watch the popular show, revealed Harry's friend JJ Chalmers who said he and the prince now spend time doing "dad chats" as he also has a son.
The TV presenter and former Strictly Come Dancing star told Radio Times that he and Harry have grown up together and he has a son called James who also loves the popular animation Octonauts.
The series follows Captain Barnacles and his crew of underwater explorers as they help rescue aquatic creatures across the world’s oceans.
Chalmers, who was injured in a bomb blast in Afghanistan in 2011, took part in Harry’s Invictus Games, which he said inspired his recovery.
He told of how he has been through “some pretty extraordinary times” with Harry.
“In some ways we’ve grown up together. When we first met, we were both young lads in the military,” Chalmers said.
“It’s been pretty lovely to move into the next stage of our life – marriage, kids – together.
“Now that we both have kids, we just do dad chat.
“I know that Archie loves The Octonauts and my son James loves it, too. The kids are a similar age and have similar interests.”
Chalmers said his children had not yet had the chance for a playdate with Archie and his younger sister Lilibet, who live in California, adding: “I’m sure they’ll get together one day soon.”
Octonauts, based on the books by Vicki Wong and Michael C Murphy, was produced for the BBC ’s CBeebies channel and now also streams on Netflix.
Harry and Meghan signed a multi-million deal with Netflix after moving to the US.
Meanwhile, Harry was in New York on Monday night, where he gave a keynote speech at the UN headquarters, talking about Nelson Mandela's legacy, as well as the challenges of climate change and poverty.
He said: "This has been a painful year, in a painful decade.
"We're living through a pandemic that continues to ravage communities in every corner of the globe, climate change wreaking havoc on our planet, with the most vulnerable suffering most of all.
"The few, weaponising lies and disinformation at the expense of the many, and from the horrific war in Ukraine to the rolling back of constitutional rights here in the United States.
"We are witnessing a global assault on democracy and freedom - the cause of Mandela's life."