Sonic the Hedgehog 2/Oil Ocean Zone

Oil Ocean Zone is a zone where Robotnik dumps his oil

Act 1
Watch out for flying sea-horses who shoot plasma at you, and the spikes, and those green things that blow you up to the air

Act 2
Keep moving to avoid drowning in the oil.

Boss
He's easy. All you have to do is hit him frequently and dodge his spiky arm he throws from the oil and a laser that will set the platform you are on ablaze.