Dan Radford, aged 37, was relaxing in the pool in Kos, Greece, on Sunday when he spotted a small boy ‘swimming strangely’.
Dan, who was hours into his family holiday at the time, swam over to check on the boy.
He said: “This tiny little lad looked like he was swimming in circles and something just didn’t look right.
“I swam over to him and it was obvious he wasn’t moving.”
Luckily, Dan’s police training kicked in and he ‘went into autopilot’.
He said: “I pulled this little lad out of the water and onto the pool side. His face was blue and he wasn’t moving.
“I thought to myself ‘I’ll be doing CPR at the side of the pool in a minute’.”
Dan said before attempting CPR, he held the boy upright and gently squeezed his chest.
He said: “The water shot out of his mouth like a hosepipe, it was obvious he had swallowed a lot.
“Then a second later, the lad started crying, which is a good sign. If he had been left a moment longer he would have died.”
During the five minutes since spotting the young boy to saving his life, Dan said the boy’s parents came over to thank him.
Dan said: “His dad was completely frozen. He hugged me, started crying and said ‘I owe you my life – you have saved my son’s life’.
“The young lad, who turned out to be three, had been wearing an inflatable life jacket. But after lunch he had taken it off and jumped back in the pool without realising.
“His parent’s backs had been turned for less than a minute and there were around 40 people about. It just goes to show how easy things like this can happen.”
The young boy was taken to hospital and remained in overnight. He is now recovering well.
Dan, who is away with wife Louise, 37, a detective constable with South Yorkshire Police, and sons Alex, nine, and Lukas, seven, said he hopes the rest of the holiday will be drama-free.
Dan, originally of High Green, but now living in Worksop, said: “It’s not the perfect way to start the holiday, but the main thing is that the young boy is safe and well.
“People at the resort keep coming up to me and calling me a hero, which gets embarrassing. I just did what anybody would have done.”