She was pulled from a deep pool by a brave onlooker.
Rescuers said a volunteer from the Llanberis mountain rescue team had been out near Llanberis Waterfall on Sunday when shouting was heard.
The girl had slipped and fell into a pool above the main waterfall while with her horrified family.
Other rescue team members were alerted as they dealt with another callout on Snowdon and the ambulance service.
A member of the child’s family went into the water to try and reach her but the youngster was then washed over the main waterfall.
Luckily an onlooker saw the girl floating in the deep pool below the falls and was able to pull her to the side, where other walkers assisted them out.
Two rescue team doctors went to the scene and assisted paramedics. Fortunately the child was still conscious and taken by ambulance to hospital at Bangor.
A Llanberis rescue team spokesman said after the drama which happened on Sunday afternoon: "The Good Samaritan who entered the bottom pool was a very strong swimmer and used to cold water but did, however, experience the effects of cold water shock with a noticeable reduction in muscle power.
“While beautiful, Llanberis Waterfall has been the scene of several fatalities and very near misses. This incident was a genuine accident, these things happen occasionally and there is no blame to be apportioned.”