Footage shows the moment a mysterious hero dived into freezing water to save a bird trapped in ice.

An unidentified young woman, who happened to be an open-water swimmer, was walking by Rickmansworth Aquadrome on Sunday (February 14) the moment onlookers spotted a great crested grebe stuck in the ice on the lake.

Chris Wicks, the founder of the non-profit CW Wildlife Rescue, has provided more insight on the bizarre incident as footage now shows the moment the woman plunged in the water and rescued the bird.

Mr Wicks said: “A young lady was passing, who is a wild water swimmer, and she stripped to her swimsuit and promptly entered the freezing water.

“She swam out to the stricken great crested grebe all the way out she was breaking the ice with her right hand and she grabbed the bird in her left hand and swam back to shore.”

In the video, the woman was seen bashing the ice while wearing gloves and struggling to climb on top and swim through the icy water.

Watford Observer: The swimmer went to rescue the bird (Photo: Facebook)The swimmer went to rescue the bird (Photo: Facebook)

When the grebe was brought to land, the swimmer was met with an applause

The founder continued: “The grebe was then rushed to CWWR and it was placed in an incubator and warmed up.”

He explained that on Monday (February 15) the bird appeared alert and “feisty”, but the ice caused some damage to the legs and feet.

A vet explained that the bird could have frostbite or nerve damage from the incident.

Watford Observer: The grebe is now being cared for (Photo: Chris Wicks)The grebe is now being cared for (Photo: Chris Wicks)

Mr Wicks continued: “The mysterious hero didn’t say who she was, she came to the rescue to see how her patient was, but then she just left saying ‘oh, it was nothing.”

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