Vashta Nerada

The base is named after Poseidon, Greek God of the ocean. In Greek mythology, the deity's son, Cyclops, was killed by Odysseus. Poseidon spent eight years exacting his vengeance, forcing Odysseus to contend with trials such as terrible sea monsters...

Shadows of the Vashta Nerada follows the same title name pattern as the first two episodes ('City of the Daleks', 'Blood of the Cybermen'). However, throughout its development the game's producers referred to it as Poseidon.

In the very first meeting between the people who went on to develop the games, the notion of creating an underwater adventure was discussed and everyone around the table was eager to produce a sub-aquatic story. Steven Moffat later revealed his desire to produce an underwater episode on television but added the budgets involved would probably prove prohibitive.

Warriors of the Deep, The Sea Devils, The Underwater Menace and The Time Monster all featured underwater bases and the Doctor also faced water-based monsters in Terror of the Zygons and Fury from the Deep. The latter story introduced the sonic screwdriver, which may prove invaluable if you're to complete Shadows of the Vashta Nerada...

Shadows of the Vashta Nerada introduces a memorable new enemy to the world of Doctor Who... Although the creature that attacks the Doctor and Amy may look like a shark it's actually a 'razor-toothed blade fin'. Early concept artwork for the monster depicted a more shocking creature, with flesh stretched over its teeth in early iterations. The monster as it now appears was considered frightening enough without being over-the-top terrifying!

One description in the script emphasizes the might of this creature, saying 'this thing would eat the Amity shark for dinner'. This is a reference to the shark in Jaws (Steven Spielberg, 1975). In his The Christmas Questions writer Phil Ford revealed this was one of his favourite movies.

The Vashta Nerada are the fourth enemy to return in the Adventure Games, with the Daleks, Cybermen and Cybermats being the first three. The Vashta Nerada first featured in Silence in the Library and Forest of the Dead, the Tenth Doctor story written by Steven Moffat that also saw River Song make her debut.

The ship visited by the Doctor and Amy is called the USS Eldridge. This was also the name of the vessel involved in the mysterious so-called 'Philadelphia Experiment'. Although it's never been proven, many claim that in 1943 the US military were somehow able to render the USS Eldridge invisible. In Shadows of the Vashta Nerada the Doctor described the project as, 'The US Navy experiments with Einstein's Unified Field Theory to make their warships invisible'.