Winning a lifesaving competition is decided by the time it takes to complete rescues - in the pool or at sea - rather than the number of people saved.
There are often pool events involving obstacle swimming and relay rescues, while on the beach there are competitions, including running on sand before diving into the sea, which mirror real-life rescue situations. Surfing on boards and sailing in boats are also included.
Both Chun-yin and Fanny are former members of the Tseung Kwan O regional swimming squad - one of the four major youth squads organised by the Hong Kong Amateur Swimming Association.
The two, 17-year-old lifesaving bronze medallion holders began to learn and practise lifesaving at Sport-Tech Association, a local lifesaving club, at Easter last year.
Last August, they joined the Hong Kong team, run by the Hong Kong Lifesaving Society. Since then, they have trained at Wan Chai swimming pool three times during weekdays and on Sundays at Shek O Beach.
Being able to swim well is a key part of lifesaving, but the two young athletes also had to master the use of surfboards. The faded scars on their arms and legs show that it has not been easy for them. Fanny says her toughest challenge has been to move the dummy, or manikin, in the water. "It weighs around 80kg and I'm the lightest member of the team at only 50kg," she says. "It's been really challenging to drag the heavy manikin from one side of the pool to the other."
To improve her strength and make it easier to lift the manikin, Fanny has put on an extra 4.5kg of muscle from regular weight training sessions since she joined the team.
Meanwhile, Chun-yin has found the team's regular weekly yoga classes demanding. "I need to do a lot of stretching in yoga because I found out my flexibility is not so good," he says. "And I've found the classes really tough." Yet the most challenging new skill for him has been riding on a ski boat. He says: "Quite apart from the speed of the boat, it's difficult to keep your balance and we often capsized at the start.
"However, fortunately, we've all put in lots of effort and have improved - even if we still have a long way to go."
As lifesaving is a practical sport, the Hong Kong team also takes part in lifesaving duties at Shek O Beach. "I have just completed my first session as a life guard at the beach," says Chun-yin. "It is a good way to practise our skills and - at the same time - help other people.
"I've enjoyed it so much that I'd like to work as a part-time life guard next year after taking my HKDSE exam."
After less than a year with the team, both Chun-yin and Fanny have yet to represent Hong Kong in competitions, but they are seen as stars of the future and will have their chance soon. They will have to compete against senior swimmers as there are no age-group categories in lifesaving events.
The duo are likely to make their Hong Kong international debuts at the National Championship in Beijing, from August 12 to 18.
The elite competitors will be aiming to qualify for the Rescue 2012 Lifesaving World Championships, to be held in Adelaide, Australia, in November.
Fanny says she is confident of representing Hong Kong at the world championships one day.
"Thanks to the help of senior teammates, I've gained a lot of confidence and I think the gap between our levels has got narrower," Fanny adds.
"Competing at the world championships is not too far off and I am hoping to improve further in the future."