Denmark’s Prince Christian may have been caught in a flash rip while swimming at a patrolled beach on Queensland’s Gold Coast, an expert says, after reports the 10-year-old son of Princess Mary and Prince Frederik was rescued by a local lifeguard.

The Royal family have been on holiday in Australia to visit Princess Mary’s family in Tasmania over Christmas, and have been seen spending time on the Gold Coast this week.

Princess Mary’s eldest son was rescued by lifeguard Nick Malcolm at Mermaid Beach on Thursday, who was on duty at the patrolled beach.

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Mr Malcolm was unaware that the boy he saw in trouble between the flags was Prince Christian.

Prince Frederik personally thanked Mr Malcolm for saving his son.

Lifeguard Nick Malcolm has chosen not to speak to the media about the incident. Photo: ABC

The Gold Coast City Council, which is responsible for lifesavers in the area, has declined to comment on the reports.

Gold Coast chief lifeguard Warren Young said Mr Malcolm had chosen not to speak to the media about the incident.

“The council hasn’t gagged Nick at all but I think he is just overwhelmed by the attention,” he said.

“I spoke to him before, he could have come down but he chose not to.”

Mr Young said Prince Frederik and Princess Mary had been grateful for Mr Malcolm’s actions.

“It was only after they’d gone and someone told him [who they were],” he said.

“They do a good job of being normal, those people, which is a credit to them I think.

“His reaction was probably governed by how interested everyone else was.

“All the guys are feeling for him because his phone is going off the hook all the time, so I think it is just a bit daunting for him.

“He’s back at work and he’s doing what he’s good at, so it all seems pretty good.”

Dr Jak McCarroll, from the School of Geosciences at Sydney University, said rips could “often hide in the background”.

“Prince Christian – he may have been caught in a little pulse, in something called a flash rip,” he said.

“What this situation highlights is how important it is to swim in a patrolled area.

Prince Christian of Denmark is on holidays with his family in Australia. Photo: Getty

“Even if you do get into trouble like the Prince, you’ll get rescued very quickly.”

Dr McCarroll said lifeguards were constantly monitoring the ocean to identify the safest areas to put the flags on beaches where there was no obvious rip channels.

“[But] you can still have occasional pulses of things called flash rips, that can briefly just send a pulse of water outside the surf zone,” he said.

“So that may have been what occurred here and as I said, it just highlights how important it is for younger swimmers and less confident swimmers swimming in a patrolled area.”

He said it was important that beach goers caught in a rip do not panic.

“As a nation, we still tend to not be aware as we should be of the risk that they pose and how best to identify them, how best to stay safe before you get in trouble, before you get in a rip current,” he said.

“Most of the time, we go through summer and there will be over 20 people per year dying in rips in Australia, with many of them through this busy holiday period of the year.

“If you do have a low level of familiarity with the beach – it’s easy what you need to do – it’s only to swim at a beach with a patrolled area and within the flags.”

Surf conditions unstable along Gold Coast

Lifeguards said surf conditions on Monday were unstable along the length of the Gold Coast.

Mr Young said strong rips had been sweeping swimmers outside of flagged areas for some days.

He said lifesaver patrols had been boosted on the Gold Coast for the summer break.

Mr Young said there had been several rescues over the past few days.

“[There are] very unstable conditions right along the coast,” he said.

“It’s only a small swell but there are some rips running out through the banks to the easterly direction.”

He said most people were swimming between the flags but there had been problems.

“Sometimes people get swept outside of the flags to a side current,” he said.

“People have been doing the right thing swimming between the flags.

“The way the currents are it only takes a little bit to be swept off your feet and we worry about people going in after hours when no flags are up.”

Mr Young also said crowds on the sand were growing as well.

He said numbers usually ramped up on Boxing Day but the heat was driving big numbers to the Gold Coast.

-ABC