A mystery swimmer plunged into freezing waters to rescue a great crested grebe.

Chris Wicks, the founder of the non-profit CW Wildlife Rescue, reports that a woman dived in the water at Rickmansworth Aquadrome on Sunday (February 14) to rescue the female bird, which was frozen in the lake.

The founder explained that a “young lady” walking in the area, who happened to be an open-water swimmer, dived in the water to rescue the bird who was stuck in ice and saved its life.

A woman was seen in Rickmansworth Aquadrome, despite freezing conditions (Photo: Facebook)

A woman was seen in Rickmansworth Aquadrome, despite freezing conditions (Photo: Facebook)

Mr Wicks says the woman broke the ice with her right hand before grabbing the bird and swimming back to the land.

Footage has circulated on social media of the moment the woman swam into the water and grabbed the bird before placing it in a net.

Watch the footage of the rescue here

And now CW Wildlife Rescue is looking after the grebe as it recovers from its icy swim.

The grebe is now recovering (Photo: Chris Wick)

The grebe is now recovering (Photo: Chris Wick)

Mr Wicks says the bird has some damage at its legs and feet, with a vet warning it could have frostbite or nerve damage from the incident.

The mysterious hero never said who she was, and as she left she said "oh it was nothing."

On Facebook, Mr Wicks wrote: “Thank you to a real hero, you definitely saved this creature’s life.”