Aqua Shield

The Water Shield (アクアバリア), also known as Bubble Shield, Aqua (アクア) and Aqua Shield, is one of the shield type power-ups that appear in the Sonic the Hedgehog series. It can be obtained by breaking item boxes with a water droplet symbol on them, which will then surround the playable character with a visible, but bouncy sphere-shaped shield, similar to a water bubble.

With a Water Shield, the playable character can take damage once without losing Rings or a life, and can move in underwater sections of the Zones without rising drowning. Also, when used by Sonic the Hedgehog in most cases, it allows the player to perform the Bounce Attack. In certain games though, the Water Shield can have different functions or have additional abilities.

The Water Shield was first introduced in Sonic the Hedgehog 3. While the Water Shield has not become as recurring power-up like the Lightning Shield, it has made some noteworthy appearances through the series.

Sonic the Hedgehog 3 and Sonic & Knuckles
The Water Shield made its first appearance in Sonic the Hedgehog 3 and it's add-on continuation Sonic & Knuckles, alongside the Flame Shield and Thunder Shield, where it can be obtained by breaking monitors with water droplet symbols. The player can also collect Water Shields from Bonus Stages by getting blue gumballs with B-letter on them.

Like other shield type power-ups, when a playable character is equipped with a Water Shield, it will protect the player from one hit worth of damage from enemy attacks and/or contact, spikes, and other environmental hazards in the Zones by keeping the player from losing Rings or a life. After blocking a damaging blow however, the Water Shield will disappear, and the player is usually send flying slightly backwards. However, the Water Shield is not able to protect the player from falling into bottomless pits, being squeezed by Crushers, or the time limit of completing the stage running out, all of which give an instant death.

While equipped with a Water Shield, the player's playable character cannot drown from staying in underwater sections of the Zones for extended periods of time, meaning that the player can remain underwater for an unlimited amount of time without having to utilize any Air Bubbles to extend his/hers time underwater.

When Sonic is using the Water Shield, it exclusively allows the player to use the Bounce Attack by pressing A- B- or C-button right after doing a Spin Jump. When bouncing back into the air from the Bounce Jump, the player can do the Bounce Jump again by pressing the A- B- or C-button again.

Besides blocking damage and allowing the player to breath underwater, the Water Shield can also deflect regular projectile shots from badniks, such as the Blastoids from Hydrocity Zone.

Sonic R
The Water Shield (called simpy as Aqua in Japanese version) made another appearance in Sonic R, where it has drastically different functionalities.

Like other items in the game, the Water Shield can be picked up by the player from floating Item Panels with blue orbs on them during the race. After obtaining it, the playable characters get surrounded by blue shield, and the player is able to walk across the water surface on race tracks, whereas without the Water Shield, the player will sink into the water and move slower. After coming back to bare land, the player will then lose Water Shield instantly.

Sonic Generations
The Water Shield (renamed as Aqua Shield) made another appearance in the console/PC version of Sonic Generations, where it is both an equipable Skill that grants the player a Water Shield once for each act, and an item box power-up for Classic Sonic. Here, the Aqua Shield retains all the effects it originally had in Sonic the Hedgehog 3 and Sonic & Knuckles.

The item boxes with the Aqua Shield appear exclusively in the Challenge Acts "Aqua Shield Challenge" and "With Your Powers Combined" where the player has to use its abilities to travers the acts. The Skill for the Aqua Shield can be bought from the Skill Shop for 300 skill points after clearing the "Aqua Shield Challenge" and cost 70 Skill points to be equipped. To activate the Skill in gameplay, the player has to press the /button.

Sonic Lost World
The Water Shield along with other elemental shields are set to make appearance in Sonic Lost World, where it can be found in item boxes with blue bubble symbols on them. Along with other power-ups and items, Water Shield is also obtainable power-up from the Miiverse, where players can share power-ups and items to each other via Miiverse.

Trivia

 * Although the Water Shield appears in Sonic & Knuckles, there are no underwater sections in any of the zones presented in the game.
 * If the player is playing as Knuckles in Sonic & Knuckles, monitors with Water Shield have red water droplet marks instead of blue. This is due to Sonic and Knuckles sharing different color palettes in the game.