Fantastic Four: World's Greatest Heroes - Season 1 - Eps 21: Atlantis Attacks
The Sub-Mariner returns, but this time he needs help to defeat Attuma, who has taken over Atlantis. While Reed, Susan, and Ben head off to help free Atlantis, Johnny stays behind and faces an attack on the city from a giant mutant whale.
About Fantastic Four: World's Greatest Heroes

Title: Fantastic Four: World's Greatest Heroes
First Air Date: 2006-09-02
Last Air Date: 2007-10-20
Status: Ended
Rating: 7.5/10 (from 89 votes)
Language: EN
Seasons: 2
Total Episodes: 26
Network: Cartoon Network
Genres: Animation, Action & Adventure, Sci-Fi & Fantasy, Kids
Production Companies: MoonScoop, Marvel Entertainment
Synopsis
Mr. Fantastic, the Invisible Woman, the Human Torch, and the Thing battle some of their greatest foes, including Doctor Doom, Ronan the Accuser, the Multiple Man, and Mole Man.
Cast

Hiro Kanagawa
Mr. Fantastic (voice)

Lara Gilchrist
Invisible Woman (voice)

Christopher Jacot
Johnny Storm (voice)

Brian Dobson
Ben Grimm (voice)