Fountain

Fountains are gimmicks that appear in various games throughout the Sonic the Hedgehog series.

Overview
Fountains are spouts that ooze out water from them. When a character jumps towards the water that is coming out, the character will be shot upwards, allowing them to reach higher platforms that they could otherwise not reach. Usually, it's compulsory to use these fountains in order to progress.

Sonic Adventure & Sonic Adventure DX: Director’s Cut
The fountain first appeared in Sonic Adventure and its enhanced port, appearing at the last portion of Speed Highway. Here, it is necessary for Sonic to use in order to reach the Egg Prison in order to finish the stage. It can also be used by Knuckles when he explores the stage.

Sonic Rivals 2
In Sonic Rivals 2, fountains appear in the first zone, Blue Coast Zone. They are activated by jumping on top of them, and when doing so, water will gush out and push the player upwards.

Sonic Unleashed
In Sonic Unleashed, fountains can only be used by Sonic during the daytime stages. This time around, it is possible to use the Homing Attack on these fountains to make it easier to use them. They appear in both 2D and 3D sections.

Sonic Colors
In Sonic Colors, fountains appear in only Aquarium Park. Like in the former game, they can be Homing Attacked, and are used to achieve greater height.