Silent Pool

The  was a lake near the Eddison Manor in England. On 8 December, 1926, Agatha Christie, the Tenth Doctor and Donna Noble drowned the Vespiform Reverend Golightly in this lake. The next day, Agatha's car was found by the side of the lake. (TV: The Unicorn and the Wasp)

Behind the scenes
The name of the lake is not mentioned in-story, but its name is on a sign.