The Doodle Dimension is an empty white place, similar to Nowhere.
Role in episode
SpongeBob and Patrick accidentally enter this dimension, and they try to find a way out. They find out they can doodle in this dimension, so they doodle with the magic pencil. This is also where DoodleBob returns. SpongeBob and Patrick in the episode eventually have a war with DoodleBob in this dimension. SpongeBob and Patrick win the war, but they are still stuck in the dimension, so they draw Doodle Sandy so she can make a portal and get them out of the doodle dimension.