The main challenge to the player would be to traverse the various flooded pipes without drowning. There is also some heavy machinery that needs to be operated in order to make progress.
The area features a cesspool filled with toxic slime that has to be purified.
Quick Level Completion
Differences from Easy to Normal
Differences from Normal to Hard / Hard+
#1: In the hallway with flashing lights, right before the room with the switches that drain and filter a tank, shoot the cracked wall to find a Bandolier.
#2: After shutting off the laser security grid, jump into the water and shoot the grate. This will take you to a room with some Adrenaline, and further along, to the Super Shotgun.
#3: After raising the security bridge from the water, swim into the opening it rose from to find a suit of Combat Armor.