The Sewers of Dross is the first in-game zone. That's where Gish begins his little "journey". The boss of The Sewers is Honey Bucket (actually, 3 of them). In The Sewers you can mostly find such enemies as Zombies and Pooblers.
Also there's two secret warp zones in this area:
- On the level 1-3. Break the very left spikes, before the hanging stones. Then just follow the tunnel and break the '?' block.
- On the level 1-4. If you manage to squeeze under the falling block on the left of the spawn point, you will fall down and then jump right on the level 4-3.