Seaside Hill is a small cluster of islands shaped like marine creatures and located near Ocean Palace. One notable residence of the isles is Sea Gate, which is home to the Seaside Town Orphanage that held Stinkfly Haughter and Swamp the Chao captive, and the home of Jonny Babineaux. Another settlement is North Pheronchurch, founded by echidnas who abandoned Ocean Palace, led by St. Morris.
The isles were visited once by Sonic and Shadow the Hedgehogs, Miles Prower, Knuckles the Echidna, Rouge the Bat, E-123 Omega, Espio the Chameleon, Vector the Crocodile, Charmy Bee, Amy Rose, Big the Cat and Cream the Rabbit, all of whom were looking for Doctor Eggman.
- "The islands were found by a group of Echidnas from Albion, who escaped a great doom there. Since the islands, now known as "Seaside Hill" were a safe haven for all those in danger, they brought many people of different species there, where they formed Sea Gate. It has existed ever since."
- —Haven the Rabbit telling her grandchildren about the islands.[Author]
Hundreds of years ago, a group of echidnas who had escaped the destruction of Albion fled towards the seas, where they found the islands. Believing the islets and rocks positions around the main hills were great for a defensive formation, they settled there, where they were safe and happy. They also built many grand platforms and buildings there, based on that of Ocean Palace, but most was submerged by the sea.
A group of echidnas who abandoned the construction of Ocean Palace, led by an influential echidna named Morris, also went to Seaside Hill. They travelled north-east of the others' settlement and founded North Pheronchurch.
Over time, they brought people of other races there, to keep them protected from whatever evils were attacking the world at the time, and Seaside Hill, as it was now called, became a safe haven for many Mobian animals. But soon, the Seaside Town was considered outdated compared to the great cities now built, such as Ruin Retreat and Everchange City, and many departed, leaving the place a quite, peaceful town.
Perhaps the most well-known location of Seaside Hill is Sea Gate, a town near the whale island.
The main area of Sea Gate, more commonly known as Seaside Town, is located on one of the bigger isles, which is home to a large hill on top of which is Station Heights.
Market Street is easily the largest area of Sea Gate, and is what is most commonly referred to as the town itself. It is a long, winding, steeply-sloped road that leads from the lower areas of the city to Seaside Station. The upper portion of the street is known as Station Heights. There are a few shops at there, including an item shop run by Quarantine Rose.
Seaside Station is a small train station that travels around the seaside isles, including other districts of the town and the beach. It rests in a large open area called Station Heights, and is roofed by the town's distinctive Bell-Chime Clock Tower.
The lower portion of Market Street is Gull Common, an open-market area popular with seagulls. Many shops are found here, including the accessory shop and armor shop run by Nial Prower and an unnamed bat. It appears to be the location of many homes as well. Neró's home is also located in Gull Common, as are the homes of his friends, Harry Farthing, Lana Pence and Gary Chrimata.
Sunset Island is reachable only by boat and is the residential area of Sea Gate, where the seaside-folk live.
Seashell Terrace is the main area of the island, where the residents of Sea Gate live in their relatively cosy seaside homes. There is a small docking area, where the boats are kept, and the Mayor's house is located there, as is the mansion belonging to Catherine Ogmore-Pritchard. It was one of the small seaside huts that Amy Rose, Cream Yamato and Big the Cat once lived in while searching for Sonic the Hedgehog, Chocola the Chao and Froggy.
The Ogmore-Pritchard Hill is home to the mansion owned by Catherine Ogmore-Pritchard, the richest woman living at Seaside Hill. It was bought by the parents of Catherine's husband, but fell into her ownership after the mysterious deaths of her parents-in-law and Mr. Ogmore-Pritchard.
- Main article: North Pheronchurch
Another town in the Seaside Hills is North Pheronchurch, which was founded by Morris and a small faction of echidnas who abandoned the construction of Ocean Palace, which was ordered by Queen Philina Flawberk.
Church of St. Morris
- Main article: Church of St. Morris
The most iconic structure of North Pheronchurch is the Church of St. Morris, a centuries-old building located on a hill in the east of town. The church was named after the first reverend, the founder Morris.
- Main article: North Pheronchurch Cemetery
The cemetery was damaged during one of Emma Morrigan's attack, but not as much as the church was. However, some gravestones were uprooted and smashed.
Tempest Vale is an isle apart from Sea Gate, but was once part of the town.
The island was chosen by the Wizard Éxypnos to home his tower, Mystiriódis Pýrgos, and was from here that he originally helped fight against evil, but later fell to evil himself and desired the Chaos Emeralds for himself. The tower was later destroyed by the returned spirit of Artériellë, Queen of Maya.
Déntra Parathalássia was a small forest on the water's edge of Tempest Vale, and was used by Éxypnos for its wood, which he used to make evil potions and crude weapons. Eventually, the spirits of the forest of Parathalássia made war on the forces of Mystiriódis Pýrgos, and, after the help of Artériellë, destroyed the Tower of Sorcery forever.
Apart from the main areas of Sea Gate, there are also several unclassified areas.
The Dásos Woods is a forest located just outside of Sea Gate, and whether it is considered part of the town is disputed. Inside the woods is Haven Gardens, the former home of many rabbits, including Sagess, Magess, Haven, Butterfly, Dragonfly and Stinkfly.
A large collection of caves and mazes exist underneath Sea Gate, though where it leads, who it was made from, and why it was created is unknown. Most of those who have ventured in there have never returned, and the only one who had returned became insane.
Mariner's Edge is a large part of Sea Gate, where Amy Rose, Cream Babineaux, Big the Cat and Cosmo the Seedrian once trained. The small pool area is popular with children, and the beaches are considered the best of the islands.
The Ocean Ruins are a large, ancient building that consists of a main entrance hall and four separate halls, as well as a secret basement area that held the third Water Spellbook before it was taken by Hendrik and his friends. The four halls each contain an elemental area – water, wind, darkness, and poison – in which the respective individuals must focus their powers on to access the basement area and obtain the spellbook.
Sonic & SpongeBob Generations
Sonic and the Steel of Darkness
Mephiles takes Sonic here in this story. While admiring the scenery, Mephiles plays a prank on Sonic by diving off a cliff and pulling the latter with him. The Blue Blur nearly drowns, but manages to swim to the surface. They get into a brief argument, but Mephiles apologizes and promises not to do anything like that again. Afterwards, the two of them relax by swimming around.
- Jonathan Babineaux
- Haven Babineaux (deceased)
- Ringo of Helios (deceased)
- Stinkfly Haughter (formerly)
- Hepzibah Babineaux-Limestone (formerly)
- Lauraleine Babineaux-Thomas (formerly)
- Lady Nevae of Adabat (possibly)
- the Hedgehog (sonicbasketballstar)
- Marina the Sea Dragon (Shadowandsilverluv19)
- Bull the Doberman (Shadowandsilverluv19)
- Nitro the Fox (Neon Duo)