If you come back outside after you stole the Arms Flash from Moreau, you will have to get through the submerged area. The first step is to jump into the boat when you see a big creature watching you.
Eventually you will get to the other side and after a few scenes you will have to climb a windmill. Above you will find a handle that will break, so you will have to get to the second windmill to get a new handle. Go inside the windmill and go down the ladder and then head towards the water.
You will see several submerged platforms, so go to the next building and then shoot the supports where the yellow tape is on them. This will cause the platform to fall into the water and give you a path. Finally, you arrive at an elevated area with a cart that you can push into the water. Do this and then run down to the lower platforms on the left. At the bottom bottom, you’ll find several switches that you can pull, causing the platforms to come out of the water.
Head right, pull the switches on the blue and orange platforms to get completely across. Be careful, because some platforms don’t stay up long, so you have to run as fast as possible.
There are more switches in this new area that you must pull out in the following order:
- Dirty white
After you pull them, run back as you came and cut straight across the platforms to keep heading for the submerged area. Follow all the sidewalks until you reach the end, but be careful. The giant Moreau-monster fish will try to crush you, so you have to time your movements well. Push the cart that comes too down into the water, then go down and run to the new area.
You will come to another switch that you can pull, which will cause the boat to come out of the water, and then you can fall on it. Walk the ship, destroy the green goo and then jump on the other end. Go inside a new windmill and destroy the lock on the ladder, then climb up and grab the handle. Use the handle to turn the ladder, then go to the other side of the platform and climb to the very top, where you can use the zipline to go to the second windmill.
Discard the one to restore energy, and then you can return to the gas station and leave the area.