Crash Bandicoot 2: Cortex Strikes Back/Sewer or Later

Another level set in the sewers, just like ../The Eel Deal/. Compared to the previous level, two new difficulties are introduced here: enemies similar to workers hanging from the ceiling to which you can only approach while their blowtorch is off and propellers which spin at very high speed and which you must necessarily destroy to go further, hitting with a spin (or slide) attack the enemies that appear in front of them. At some point you will come to a fork. You should go right first, where you will find a (!) box and the detonator to blow up the Nitro boxes: activate them both. Then go back and go left. At the bottom you will find the crystal. Go back again and go right to continue the level.

There is a bonus area about halfway along the path. First you'll need to use your slide to go under piles of metal crates, destroying the boxes beneath them. Next, you'll have to destroy boxes placed on top of dangerous Nitro boxes. So be careful not to touch them while jumping on the boxes.

Getting the first gem
The first gem is obtained as usual by breaking all the boxes. This shouldn't cause you particular problems in this level.

Getting the second gem
In order to get this gem, you must have already obtained the yellow gem from the previous level, ../Plant Food/. Along the way, shortly after the start, you will find the gem on the floor, which will lead you to a hidden area. This path is quite insidious, as you will have to cross pools where the water is constantly electrified. You must therefore take advantage of the floating platforms to avoid falling into the water. Along the way you will find the gem. At the bottom then, you will find the yellow gem again which will take you back to the main level, even if at a more advanced point than the one where you left it. Note: There are no boxes in this secret path, so you can get the first gem without entering it.