Everyone loves water levels in Sonic games. Dat drowning music,man. Anyway. You can raise and lower the water level with the 3 switches on the upper levels. Knuckles can find a power up hidden down a shaft. Lower the water to the lowest level to get down it. You'll have to swim through a water tunnel and nearly drown to get it. The Air Necklace however means Knuckles will never drown again. Took me a while to figure out how to get the last emerald piece,with a spin jump.
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