Aquatic Mine

Aquatic Mine is the eighth stage in the Hero storyline of Sonic Adventure 2 and is playable by Knuckles. It is set in an abandoned coal mine, accessible through the sewer system of the Capital City. The level follows a theme similar to that established in Labyrinth Zone, with changing water levels, operated by switches on the two uppermost levels, and mineshafts leading to dead-ends and pits. This level may appear unnerving to some, on first play, due to the limited air supplies underwater, however a shaft accessible from the lower levels will lead the player to Knuckles' Air Necklace upgrade, allowing an unlimited air supply while underwater.