The first episode of "Spartakus and the Sun Beneath the Sea"
For those that a) don't remember this show, and b) don't understand French (that title, btw, means "The Engulfed Worlds"), the story goes as follows:
Bob (Matt in the English version) and his sister Rebecca are spelunking in some cave somewhere. Why their parents don't seem to notice is something I never thought about. Anyway, Rebecca gets in some trouble, and is only rescued by a living ship called ShagShag (Tehrig), and its occupants, the humanoid Arkana and the pangolin-esque Bic and Bac, Arkadia's oldest living creatures (who, when they literally put their heads together, create a "flashbic").
Here, we learn the backstory: Many thousands of years ago, the great city Arkadia was lost in a Great Cataclysm that absorbed it into the earth. Somehow, defying all known laws of nature, the Arkadians managed to survive and created an artificial sun, Shagma (Tehra). Years passed, and Shagma's condition began to deteriorate. In a last bid for hope, two Arkadian kids broke a sacred law and entered the archives, where they learned that they once lived on the surface and possessed these things called "legs". So, for the holy day of the Auracyte, they unveiled Arkana, who revealed that she was like one of the ancestors. Finding no other option, the Arkadians sent ShagShag through some Shagmir Rays (Tehric Rays) to the surface, where our story begins.
With help now acquired, ShagShag (who is a sentient ship) intends to use the Shagmir rays to go back home. But their efforts are thwarted at the last moment by the Pirates of the Lake, who capture ShagShag, Arkana and either Bic or Bac (I can't remember which). Luckily for Bob and Rebecca, a Bakar warrior named Spartakus listened in, and is ready to rescue them. Bob, Rebecca and Spartakus go inside the pirates' ship-thing and Rescue Arkana, but, in order to evade the pirates, ShagShag is forced to go away from the Shagmir rays, temporarily dissolve and go through what appears to be a block of purple ice. This traps our heroes, who now have to rely on Spartakus to return to Arkadia.
I used to have a comic book of this story, although, IIRC, it ended right where the Tehric Rays (which the book misspelt as "Terric rays") appeared, with Spartakus suddenly becoming a total git and deliberately leading them away. It also put the story in a proper chronological order, played fast and loose with spelling ("Auracyte" became "Oracite", and Tehra/Tehrig became "Terra/Terrig").