One recent afternoon at a popular beach in Australia, a 10-year-old boy found himself being dragged out from shallow water near the shore by a sudden underwater current.
Spotting the incident - which happens all too often on Australian beaches - a lifeguard rushed out to save the boy and delivered him to the arms of his frantic parents.
But it turned out that the boy was Prince Christian of Denmark. He was at the beach on Queensland's Gold Coast with his parents, Prince Frederik and Australian-born Princess Mary. The incident, which happened on Dec 17, made national headlines and lifeguard Nick Malcolm was hailed a hero.
"It was just a standard rescue - doesn't matter that he's a royal," Mr Malcolm told local reporters.
But the incident highlighted a dangerous phenomenon that receives relatively little attention despite its deadly toll: rips, or underwater currents.
Labelled "Australia's silent killer", rips kill far more people than sharks or bushfires - about 21 people a year, many of them tourists totally unaware of the danger that lurks along the shorelines. People getting caught in rips account for about 89 per cent of beach rescues - up to 15,000 a year.
The incident with Prince Christian occurred just as locals and tourists began flocking to Australian beaches for the summer.
Much of the recent focus has been on a spate of shark attacks, but many beachgoers seem oblivious to the danger of rips, which pose a much bigger threat. Australia has about 11,000 beaches, which have about 17,000 different rips happening at any given time.
They occur when water comes ashore as waves and then flows back to sea, forming deep underwater channels. The channels, or rips, can occur every 150m to 200m along a beach but are often difficult to spot. The authorities say rips are actually easy to avoid if people understand the threat and know how to respond.
In many cases, simple tips can prevent drownings, including avoiding trying to swim against the rip.
Studies have shown that rips do not actually pull people underwater but take swimmers away from the beach. For this reason, swimmers should not try to swim against the current, which only leads to fatigue and can cause people to panic and lose their bearings.
Surf Life Saving Australia says the first step is to "stay calm, float and raise an arm to attract attention". The association says beachgoers should swim at patrolled beaches and stay between the flags to ensure they are being watched by lifeguards.
An expert who has studied Australian rips, Dr Rob Brander, from the University of New South Wales, said the problem was ignorance, not the actual currents. He has called for better signage at Australian beaches, video screenings on international flights, television and cinema advertisements, and improved education campaigns at schools.
Dr Brander said research has shown that rips work in different ways, so there is no one single solution to escaping one.
"First of all, don't panic," he told The Australian. "Rips just take you for a ride. If you want to swim, start swimming towards the white water. Swim parallel. If that is not working, go back to floating."
In the state of Queensland, lifeguards and a University of Queensland marketing manager have produced a new water-resistant booklet which advises on surf safety in 11 different languages, including Japanese, Chinese, Malay, Arabic and Indonesian. Thirty-five of the state's 78 drowning fatalities since 2005 have been tourists or migrants.
"Many international visitors don't understand the surf," Mr Mark Shroder, from the University of Queensland, told ABC News. "They think the calm part of the waves is the best spot but it's where rips are."
Dr Brander said the most important steps were to avoid panicking, conserve energy and "constantly reassess your situation". He said Australia was far too complacent about educating locals and tourists about the risks.
"It frustrates me that we haven't got adequate signage on beaches and that signage is really underdone," he said. "Maybe it is because we don't want to scare tourists, but nobody should drown. Nobody."
Fortunately for Prince Christian, he appeared to be well aware of the beach rules and was swimming between the flags.
"He was a really good swimmer - it helped that he didn't panic," said Mr Malcolm, who rescued him.