The Chinese water deer was found about four metres down in a partially water-filled hole on a farm in Chatteris on Wednesday, October 7.
The rescue was carried out by the RSPCA with assistance from Cambridgeshire Fire and Rescue Service.
John Woods, animal rescue officer at the RSPCA, said: “This poor deer couldn’t climb out of the hole and was completely stuck.
“The Chatteris and Dogsthorpe crew kindly attended and helped use their ladders to get into the reservoir and get the deer out.
“The deer was active and well with no injuries and soon made a swift exit as soon as they had been freed.
“Not even a nod, a wink or a polite thank you after all that effort.
“Seriously though, it’s the highlight of our job being able to save and release animals back into the wild like this.
“I’d like to say a massive thank you to Cambridgeshire Fire and Rescue Service for coming to the rescue and helping get the job done.
“It’s a great reminder of what we can achieve together for animal welfare.”
Chinese water deer are native to China and Korea and are only found in a small part of the UK.
They are most commonly seen in Bedfordshire, Cambridgeshire and Norfolk, having originally escaped from zoos in the 18 and 1900s.
The deer do not have antlers but are instead recognised by their prominent tusks.
They favour habitats such as reed beds, river shores, woodlands and fields, making the wet fenlands of Cambridgeshire and Norfolk an ideal environment.
For expert advice on helping deer, visit the RSPCA’s website.
If you want to help the RSPCA continue to rescue animals in need, visit rspca.org.uk/give.