In his first stage of the game, Sonic races across the picturesque beaches of Emerald Coast, searching for Tails, who has crashed his prototype plane somewhere in the area. Despite the expected serenity of the gorgeous beaches, it is populated by a number of Eggman's destructive Badniks, as well as an Orca, which will hurt you if you touch it. The presence of hostile robots seems to have forced beach-goers to temporarily evacuate the coast, leaving Sonic on his own impromptu race course to dash through.
Big the Cat has entered this gorgeous locale to once again fish for Froggy. Due to the stage being located literally right next to a vast expanse of ocean, Big has many other fish to distract himself with catching. If Big is equipped with the Life Belt, he may just discover a secret area under a rock, with even more fish for him to catch. The part of Emerald Coast that Big fishes in is located in Sonic's "Azure Blue World" section of the stage, right after the iconic whale chase. In the end, he finds Froggy, only for Froggy to be immediately abducted by E-102 Gamma. This is his third stage.
E-102 Gamma has entered Emerald Coast to find and capture Froggy for his master, Dr. Eggman. Though he only travels through a small section of the first part of the stage with small modifications to some wood platforms, there is a surprisingly large number of Badniks for Gamma to use as target practice while he searches.
In Sonic the Hedgehog, Sonic's version of Wave Ocean, a level very similar to Emerald Coast, has a segment in which the player deals with an Orca that smashes through a bridge, similar to the Orca that chases Sonic in Emerald Coast.
There's a real life beach that also has the name of "Emerald Coast" in Destin, Florida. With its hotels lining the coast it bears a striking resemblance to the one seen in Sonic Adventure.
Tails, Knuckles and Amy can all be playable in Emerald Coast Act 1 using glitches and exploits in the adventure field. However, none of these characters will be playable once the player reaches Act 2. This ability was removed in the Xbox Live and PSN re-release versions of the game.