Seaside Island

Bygone Island is the main setting of the Sonic Boom series and where Sonic and his friends live. The island is shown to have various regions with climates and environments different from one another, such as a region of ice and snow neighboring a tropical forest.

Bygone Island is frequently attacked by Dr. Eggman from his lair which lies just off the coast of the island.

Sonic Boom: Rise of Lyric
A millennium ago, Bygone Island was seemingly an outpost for the Ancients, given the countless local ruins of their civilization.

In the present day, the local Village had been heavily damaged, so reconstruction projects were set up. Meanwhile, the island came under the approaching threat of the villainous Lyric the Last Ancient and his forces. However, the majority of the villagers were more concerned with the re-election of Mayor Fink. Eventually, Team Sonic came to Bygone Island to secure the Chaos Crystals. Eluding both Lyric and his temporary ally Dr. Eggman while on the island, Team Sonic used Bygone Island's Crystal Locks to reach the Chaos Crystals before defeating Lyric for good. A party was soon after held in the Village to celebrate Team Sonic's victory, where Lyric's remaining Destruction Troops were scrapped.

Sonic Boom: Shattered Crystal
Learning that Amy had been kidnapped by Lyric the Last Ancient, Sonic ventured to Seaside Coast to assemble Tails and Sticks for a rescue mission. After reigning in a reckless Sticks, Tails devised a way to track Amy, making the group head for the Scrapyard.

Archie Comics
After driving Dr. Eggman's Big Boy off Bygone Island, Team Sonic helped Tails reclaim his house from the Rock-cyborg. The doctor soon returned with the Big Boy, but Team Sonic managed to drive it away again despite complications brought on by Knuckles' attempts to prove himself. However, Amy lost her piko hammer in the process, so most of Team Sonic searched the island for it while Sticks tried to comfort Amy. They eventually found it, after it was launched back to Bygone Island from Eggman's lair. Team Sonic was attacked by an upgraded Big Boy again not long after, but thanks to Sticks and the Rock of Justice, the heroes pulled off a narrow victory.

Having the urge to destroy a bridge, Eggman made several trips to Bygone Island to sell a bridge and later earn the villagers' trusts for future schemes, only for the majority of his attempts to end badly. Not long after, Eggman set up the Go-kart Pan-island Grand Prix on Bygone Island and got Team Sonic to compete with him in a race around the island. Despite Eggman cheating, Sonic won the race, although Eggman got the data he needed for Project Hodge Podge. When the Maverick Hunters then arrived on Bygone Island, Sticks and her team joined them on a cross-dimensional adventure, which she would tell to her team afterwards, though none believed her.

When Sonic allowed Kyle the Gorilla to crash with him after getting him out of Eggman's lair, the hedgehog spent some time helping Kyle get a job on Bygone Island. Eggman himself would soon after spy on Team Sonic with cameras around Bygone Island to find his lost earpiece.

Sonic Dash 2: Sonic Boom
In Sonic Dash 2: Sonic Boom, Bygone Island appears as two of the environments the players can travel through during their runs. One of the environments include the island's tropical wilderness and the other takes the player through Unnamed Village.

Topography
Bygone Island has various regions, often different from one another, such as tropical forests, lush beaches, frigid, volcanos and desert canyons.

Areas

 * Coral Bay
 * Crater Lake
 * Danger Falls
 * East Forest
 * Hazard Jungle
 * Hidden Meadows
 * Jeopardy Lake
 * Mount Safety
 * Mystery Bay
 * Peril River
 * Pleasant Gardens
 * Seaside Coast
 * Valley of Broken Glass
 * Valley of the Cubots
 * West Forest

Settlements and structures

 * Amy's House
 * Buddy Buddy Temple (destroyed)
 * Gogoba Village
 * Seaside Harbor Light
 * Sticks' Burrow
 * Sonic's Shack
 * Tails' House
 * Tails' Workshop
 * Unnamed Village
 * Village Center

Unverified areas

 * Claggerhorn
 * Lands of the Doomed
 * Field of Baby Ducks
 * Staircase of Terrifying Slipperiness

Trivia

 * As of yet, the island is not actually named in the TV series. However, it is identified in Sonic Boom: Rise of Lyric where it is one of the hub worlds in the game.
 * The whole overworld in Sonic Boom: Shattered Crystal is also unnamed.
 * As implied by T.W Braker's circus truck in "Circus of Plunders", traffic on Bygone Island drives on the right. However, in "Chez Amy", Amy says none of the villagers own cars.