This zone will be most likely be remembered as the most annoying of the game. It is another set of ruins mostly underwater. When Sonic is submerged, his speed is about half that of normal. During progress of each act air must be located as Sonic can only hold his breath for a short amount of time. When Sonic’s air supply is running out a countdown starts. His air supply can be replenished by leaping out of the water which is not always possible or by grabbing a large air bubble when it emerges. This can be timed but can be tricky so just assume it is random and to give enough time.

Act 2 start off with Sonic rocketing down rapids into the murky depths below.

Hazards to avoid include mines swinging on chains, spikes, spears, poison spitting statues and of course drowning. The water level is not always static. Some areas fill up rapidly.

Act 1	Act 1
Act 2	Act 2
Act 3	Act 3
Robotnik	Robotnik

The Robotnik encounter is basically a chase. He does not pose any real challenge himself. Sonic chases him up a hazard filled shaft which soon fills with water. Speed is of most importance should becoming submerged is dangerous since the only place to get air except at the very top.