Lake Silencio

Lake Silencio was located in Utah, situated on the Plain of Sighs.

History
River Song was abducted by the Silence and Kovarian, placed in an Apollo spacesuit and submerged in the lake to await the the Doctor. This horrified her as it meant the tale about when the Doctor is supposed to die is true. (TV: Closing Time)

On 22 April 2011, the Doctor brought his companions to the lake for a picnic. During the picnic, Amy Pond saw a Silent in the distance, but promptly forgot about it when she looked away. Later in the picnic, the earlier version of River Song in an Apollo spacesuit emerged from the lake and shot the Doctor three times, apparently killing him. Amy Pond, Rory Williams, and River placed his body into a nearby boat, set it aflame with gasoline provided by an elderly Canton Delaware and pushed it into the lake. (TV: The Impossible Astronaut)

The Teselecta's database contained a record of the Doctor's death at this lake. (TV: Let's Kill Hitler)

Dorium Maldovar claimed that the Silence chose this spot because it was a "still point in time", making it easier to create a fixed point in time. (TV : The Wedding of River Song)

In an alternate timeline, River Song refused to kill the Doctor. This caused time to collapse. All of history happened at once. The Doctor averted this timeline by persuading River that his death was necessary and revealing to her that she had shot not him, but the Teselecta, which had taken the Doctor's form. The Doctor was present at his 'death', but was safe inside the Teselecta and "barely got singed" by the funeral pyre. (TV: The Wedding of River Song)

Later, River Song bought the Doctor a t-shirt saying "I died at Lake Silencio and all my wife got me was this lousy t-shirt". (PROSE: Houdini and The Space Cuckoos)

Behind the scenes

 * "Silencio" is the Spanish word for silence.