A five-year-old girl was found floating motionless in the main pool of Adventure World, a Perth theme park, on Saturday.
A passerby spotted the little girl floating face down in the water and came to her rescue.
The woman, who does not wish to be identified, told 9News a life guard rushed over to administer CPR after she pulled the child out of the water.
Paramedics were on the scene within minutes and rushed the child to hospital once she had been stabilised.
Witnesses have praised the professionalism of staff at the theme park.
"[It was] very scary," one bystander told 9News.
"The way they protected the other children as well, by just clearing the area, clearing the pool — very professionally done."
Adventure World has released a statement thanking guests who helped and sent their well-wishes to the young girl and her family.
Perth Children's Hospital said the girl is still being monitored, but she is stable and expected to stay that way.
