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Sonic X
An Underground Odyssey

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"An Underground Odyssey" is the sixty-second episode of the anime series, Sonic X. It first aired on 20 March 2005 and 12 November 2005 in France and the United States respectively.




Japanese version

English version

  • "Gotta Go Fast" - Opening theme (USA and CAN)
  • "Sonic X" - Opening theme (AUS, NZ and UK)
  • "Gotta Go Fast" (shortened) - Closing theme


The show opens with a sequence inside Cosmo's ship and ends when Scarship (see previous episode) destroys it, leaving Cosmo alone. Then, the Blue Typhoon lands on a new planet. It seems that there is a Chaos Emerald nearby. Tails, Knuckles and Cosmo follow the emerald's track to an abandoned city. Knuckles discovers a deep gorge with a cave. Tails and Cosmo enter, but Cosmo accidentally pushes a button which launches an avalanche and seals them inside the cave. Tails is knocked unconscious, but Cosmo wakes him up and he dizzily sits up and holds his head where he got hit during the avalanche and Cosmo puts a bandage on his head.

Tails still receives the emerald's signal on his Comlink, and he and Cosmo pursue their searches. Inside the Blue Typhoon, Amy receives a distress call from Knuckles and she informs Chris, Sonic, Cream and Cheese (who are all aboard the X-Tornado) of the situation.

Inside the cave, Tails and Cosmo discover a big factory full of Metarex. They enter unnoticed and they find the Chaos Emerald inside a manufacturing plant of fake emeralds made for Operation Duplicate. They are found out by the Metarex, but they are able to escape with the real emerald. Then, Tails fools the Metarex with special "fireflies". Regardless, Tails and Cosmo are found and retrieved by the Metarex and Tails gets knocked out and drops the Chaos Emerald. The Metarex steal it. However, Cosmo manages to wake Tails up and he yells to give the Emerald back. The Metarex tells them its impossible and Tails fights it. The Chaos Emerald is dropped and Cosmo retrieves it, but Tails is caught by a Metarex. Fortunately for them, Sonic, Chris, Amy, Cream and Cheese arrive to help them. Together, they defeat the Metarex and they are able to escape with the Chaos Emerald. Tails and Cosmo also are starting to have feelings for each other.

Eyecatch cards

Regional differences

  • The opening scenes within Cosmo's ship were given a vintage effect in the English dub. The same goes for the flashbacks to the ship exploding and Galaxina.
  • Right after Cosmo and Galaxina leave their mother, a long shot of her was removed from the dub.
  • There is no mention of the abandoned city's Planet Egg in the dub.
  • The entirety of Cosmo's inner monologue blaming herself for the conflicts that ensued with Sonic and the gang was cut in the dub.
  • Shortly thereafter, the scene of Tails telling Cosmo not to blame herself and not to worry even if she feels a little scared was cut as well.
  • The Metarex in the base were silent in the original version. They were given quiet breathing/growling noises in the dub.
  • A brief three second shot of Cosmo noticing the fake emeralds and going to them was cut from the dub.
  • The dub removes the message "now loading..." from Tails' wristwatch as the emerald's data is being downloaded.
  • The flashback of Super Sonic fighting Perfect Chaos also has a vintage effect on it in the dub.
  • A small shot of a worried Cosmo running to Tails after he is smacked by the Metarex Viper was cut in the dub.

Title in other languages

Language Title Translation
Japanese 地下渓谷の秘密 Secret of the Underground Canyon
French Le souterrain secret The secret underground
German Odyssee im Untergrund Odyssey in the underground
Italian Odissea nei sotterranei Odyssey in the underground
Spanish El secreto del cañón subterráneo The secret of the underground canyon
Polish Podziemny Sekret Underground Secret
Russian Тайна подземного ущелья The secret of the underground canyon
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