Level 2
"Pipe Dreams"
Level 2 is a long hallway that has open ways to other hallways, surrounded by pipes and the sounds of water flowing through. The small lights under the pipes give you an idea of where to go. Although the level isn't exactly straightforward, it's not a massive area and casually walking will have you in Level 3, even if you haven't gotten a clue where to go.
In-Game
There have been first-time occurrences of Smilers. An exit can be found after dealing with them which leads to Level 3.