If you only had seconds to spot a drowning child, could you do it?
It's a parent's worst nightmare: turning their back on their swimming children for half a second, only to turn back and see they're in desperate trouble.
But that's the speed in which lifeguards operate at in order to save lives.
A powerful video has emerged online of what appears to be a lifeguard whose extremely fast reactions save a child from drowning - in the middle of a crowded swimming pool.
The footage, posted by Lifeguard Rescue to YouTube, shows a wave pool crowded with young children and toy rubber rings.