

Take cover behind the concrete slab until the gunfire stops. As soon as the gunfire stops, run out and turn to the left. You’ll be hit, but you shouldn’t take much damage. The helicopter should send a barrage into the wood. Duck under that little wood structure before the water. There is nothing you can do to kill it without cheating. There’s a Combine hunter helicopter up ahead and it will chase you with machine guns blazing. Be careful about knocking them off when you step up to the ramp. Just pick up cider blocks and lay them down on the high end of the seesaw to create a ramp up to the second level. Then run along the platform and jump to the other side and double back to duck into the next sewer entrance. Stop here and use it for cover while you pick off the combine lining the canal. There is a raised board near the base next to a dead civilian. Swim to the end and then turn around to get onto the slanted platform on the left side that has fallen into the water. Get past the gate and jump back into the water. Swim down the canal until you hit the gate and look for the ladder up to the platform on the right. Just jump in and stay below the surface to avoid the blasts. They’re already tossing explosive barrels into the water, so be ready for a fight. Go under the barnacles and move up the exit on the right slope past the skeletons. If it doesn’t then they’ll be busy trying to eat the bones the other barnacles cough up. Once one of the tongues grabs it, shoot the barrel twice to set it on fire. Grab an explosive barrel and throw it down the slope. There’s a whole pack of barnacles at the bottom of the next slope. Slip under them while they’re trying to eat it. Throw one of the first barrels into the two barnacles at the bottom of the first slope.

It’s easier to just save the ammo and use the barrels though. If you slip and one of them gets a hold of you, then look up and start shooting it as quickly as you can. Be careful and make deliberate moves and watch out for the barnacles. You’ll also notice that the floor has very little traction. As you enter the tunnel, you’ll see two barnacles up ahead.
