You will come to a four way juncture. Computer 1 is to the left, computer 2 is to the right, and computer 3 is straight ahead. Go to each computer and the information will be downloaded automatically whenyou touch them. Sewer is just a maze, find your way out. Find Research camp.
Hills are just a maze, but it can be tough.
The trick to this level is going down all the pistons and activating every switch. This will open doors for you to continue. Go back up to one of the pistons. The far right one in the room with the four pistons. Go down that one to lower room.