Doctor Who: Every Tenth Doctor Episode Ranked From Worst To Best

One of the many smart decisions made by The Waters of Mars is the way it introduces the idea of a fixed point right at the start.

The Doctor instantly knows that not only is everyone inside Bowie Base One doomed, but that he could probably save them if he wanted to. This ratchets up the tension right from the word go and it doesn't let up for the next hour, as you're just sat there waiting for the proverbial to hit the fan.

And when it does hit the fan, it's some of the scariest Doctor Who that's ever been made. The makeup and effects work that created the water zombies is pure nightmare fuel, and the idea of a single drop of water sealing your doom is a constant lingering threat throughout.

This culminates in a tragic final 15 minutes in which the Doctor is forced to listen to the entire crew die, before changing his mind and becoming the Time Lord Victorious! The way Tennant flips that switch is insanely good, revealing a new layer to his Doctor (and his own performances) in his penultimate story.

The Waters of Mars is smart, grown-up, and thrilling Doctor Who.