Sonic Underground - Season 1 - Eps 7: The Deepest Fear
On a trip to Port Mobius, Sonic, Manic and Sonia are told that ships are sinking due to the Mobian sea-beast. The legendary story becomes fishy when the Hedgehogs meet Captain Squeegee who informs them of a scam in which townspeople must rely upon Robotnik for protection from the sea monster, when in reality it is Robotnik who is sinking ships, not a monster. Sonic must overcome his fear of water and the monster to find the truth and thereby ending the fears of the sea side town.
About Sonic Underground

Title: Sonic Underground
First Air Date: 1999-08-30
Last Air Date: 1999-10-22
Status: Ended
Rating: 6.9/10 (from 145 votes)
Language: EN
Seasons: 2
Total Episodes: 40
Network: TF1 Syndication
Genres: Action & Adventure, Animation, Kids
Production Companies: Les Studios Tex SARL, DiC Entertainment, TF1
Synopsis
Sonic, Sonia, and Manic are the children of Queen Aleena Hedgehog, the rightful ruler of Mobius, and are pursued relentlessly by Doctor Robotnik and his bumbling bounty hunters sidekicks, Sleet and Dingo. As infants, the siblings were separated and placed in hiding to fulfill a prophecy made by the Oracle of Delphius that the triplets would grow up to find their estranged mother, overthrow Robotnik, and take their places once more as Mobius' rightful rulers.
Cast

Jaleel White
Sonic / Manic / Sonia (voice)

Garry Chalk
Dr. Robotnik (voice)

Maurice LaMarche
Sleet (voice)

Peter Wilds
Dingo (voice)

Gail Webster
Queen Aleena (voice)

Ian James Corlett
Cyrus (voice)

Sam Vincent
Sonic (singing voice)

Tyley Ross
Manic (singing voice)

Stevie Vallance
Sonia (singing voice)