"The Volcanic Venture" is the forty-eighth episode of the anime series, Sonic X. It first aired on 29 February 2004 and 12 March 2005 in Japan and the United States respectively.
- Sonic the Hedgehog
- Miles "Tails" Prower
- Knuckles the Echidna
- Amy Rose
- Rouge the Bat
- Christopher Thorndyke
- Chuck Thorndyke
- Mr. Tanaka
- Dr. Cadberry
- Dr. Eggman
- Mothmacin (Only appearance)
- Mongroun (Only appearance)
- "Gotta Go Fast" - Opening theme (USA and CAN)
- "Sonic X" - Opening theme (AUS, NZ and UK)
- "Gotta Go Fast" (shortened) - Closing theme
After his defeat in the last episode, Dr. Eggman has fled into the volcano at the world's bellybutton. Sonic and his allies prepare to pursue him with the X Cyclone. Rouge is reluctant to go underground at first (it would ruin her skin, and it's much more a task for an echidna) but when Mr. Tanaka uncovers a sample of Ermurasium--which contains a beautiful gemstone used by the ancient Murasians--she becomes much more enthusiastic.
Sonic, Knuckles and Rouge find the dirt inside the volcano to be unstable, so they make slow progress through narrow passages rather than tunneling. After travelling past lava flows and through an underground river, they arrive at an underground city of Murasian ruins, lit by an artificial sun made of Ermurasium. In the original version, Dr. Cadberry explains that the Murasians attributed their city's demise to a dragon god, which does not scare Rouge or Knuckles in the least.
Eggman is camping in the ruins, and sends Decoe and Bocoe to forage for food. They find what appears to be a large red fruit, but it is actually the end of a antennae on a massive moth named Mothmacin. Chris tries to help the fleeing robots, but all three of them fall into a deep pit and land right at Eggman's feet.
Meanwhile, Dr. Cadberry and Chuck watch for signs of the volcano's activity. The volcano serves to let off pressure on the world's bellybutton, and it is due to erupt soon. They advise Sonic and his friends that they will have to leave soon to avoid the eruption. Sonic and Rouge head off to find Chris as Eggman zeroes in on the location of the world's bellybutton. As he prepares to set a detonator, Bokkun arrives in a panic, leading a massive, ancient drill robot named Mongroun that emerged from the volcano. Eggman and Bokkun escape, leaving Decoe, Bocoe, and Chris behind with Rouge as the volcano begins erupting. Rouge's attacks are ineffective, so Chris runs to the detonator and tries to lead the robot to him.
Decoe and Bocoe decide it is time to repay Chris for his help against Mothmacin. For a moment, they plan on transforming into a large and impressive mech... but when they attempt the feat, they find that they cannot actually do it. Mongroun knocks them into pieces with his tail as Sonic, Tails, and Knuckles arrive in the X Tornado. Sonic plants the detonator, and the robot explodes, triggering the volcano. Sonic and his friends all escape to Chris' boat, though for the moment, it seems that Decoe and Bocoe were unable to leave in time.
As the friends consider the robots' apparent sacrifice, Chris calls their names in a mournful gesture... and they emerge from the back of the boat with Tails and Chuck, who have brought them along and repaired them. They express their gratitude and declare that they are fed up with Eggman's selfishness--and they are leaving him.
- In the original version, the material Tanaka finds is called "Harashi mineral". In the English dub it is "Ermurasium".
- Some conversations between Sonic, Knuckles and Rouge are changed.
- In the original version, when Decoe and Bocoe do their imaginary transformation, they say nothing. In the English dub, a whole description was added.
- Right after Decoe and Bocoe's imaginary transformation, there is a shot of Mongroun with a thought bubble displaying a strong-looking robot, only for the thought bubble to pop and give him a red anger vein.
- In the Japanese version, Dr. Atsumi said he was kicked out of the university for suggesting the existence of Murashia.
- In the Japanese version, Decoe and Bocoe were destroyed when the island volcano erupted, and Tails and Chuck repaired them. In the English dub, this was changed to have Decoe and Bocoe say that they escaped from the island in time.
Title in other languages
|Japanese||ソニック対地底怪獣||Sonic VS the Monster from Underground|
|French||Le continent disparu||The lost continent|
|German||Die Vulkaninsel||The volcanic island|
|Italian||Avventura nel vulcano||Adventure in the volcano|
|Spanish||Sonic contra el monstruo subterráneo||Sonic against the underground monster|
|Russian||Соник против подземного монстра||Sonic against the underground monster|
- The title card resembles a "Godzilla vs." movie title.
- This episode's title is a reference to the Japanese title of the 1965 science fiction kaiju film Frankenstein Conquers the World.
- Mothmacin has a near resemblance to Mothra. Mongroun also bears a resemblance to Moguera.