Air Necklace

The Air Necklace is an optional upgrade for Knuckles the Echidna. This upgrade allows Knuckles to stay underwater for an unlimited amount of time without drowning (greatly useful during Knuckles' section of the Cannon's Core). The Air Necklace upgrade is found in the Aquatic Mine and is usually rather hard to find and hard to reach since the path is ridden with water spikes. It's also very dangerous because if Knuckles doesn't reach the upgrade (which is above ground on top of a water tunnel) he'll drown, causing the player to start over again.