Doctor Who: 20 Things You Didn’t Know About The Waters Of Mars

There were two storylines in the running for this episode during its early days: RTD's Mars-based plot, and the aforementioned hotel idea, which was written by Phil Ford.

RTD eventually picked his idea, partially due to a timely announcement made by NASA.

Shortly before the two writers were set to meet to discuss the episode, it was revealed that NASA's Phoenix Mars Lander had discovered frozen water on the surface of the red planet.

RTD took this as a sign to push ahead with his idea, and came up with the concept of a water-based monster for the Doctor to fight.

Also inspiring the soggy nature of the story's villain was the animated water in James Cameron's seminal 1989 sci-fi flick, The Abyss.

Good thing the Phoenix didn't discover jelly on Mars instead!