Walkthrough

Sewers (Connecting to Amusement Park)

"Go to the lighthouse on the lake, and to the center of the amusement park. Make haste. You are the only hope."

East and South Tunnels

After the brief cutscene of Cybil, get the Sewer Map (Connecting to Amusement Park) on the wall and head down the tunnel. If you hold L2 you can spot a couple Hanged Scratchers on the roof, which you can safely shoot down from a distance, and another on the ground ahead. Continue past them and take a right, since the path ahead only continues into a dead-end with more Scratchers.

Make your way west towards the center tunnel to encounter absolutely terrifying new creatures called Mumblers. I wouldn't blame you for wetting yourself. Either blast them or just run past and you'll find a Health Drink at the west end of the path where it connects to the center tunnel.

Center Tunnel

Before heading northward, be sure to check out the south of the center tunnel for a Health Drink and Handgun Bullets. Then proceed to the north past two more Mumblers and potentially a Scratcher. Kill them if you feel unsure about having all these enemies chase you, but otherwise you can just run past them all. Take a left and head into the west tunnel.

West Tunnel

You may soon encounter a Mumbler approaching you, but there's room to slip by it on the right. You'll hear a loud bang while passing it, and I'd advise you to just keep your ass running instead of finding out what caused it. Agreed?

Mind the holes in the grating on both sides and you'll soon encounter nearly the entire floor missing with a corpse in the water, but you can slip by on the narrow strip on the right.

Soon you'll spot some merry-go-round horses and a ladder at the end of the path. Quickly approach and ascend it to exit the sewers. Note that locating and using the ladder fairly quickly is important since the craziness that is chasing you from behind, including Mumblers and Scratchers, can catch and corner you if you get caught up on either side. Take a deep breather as you exit to the surface. You survived. Well, hopefully you did.