At the beginning of "Weirdmageddon Part 1," Bill traps Mabel inside this prison bubble. Later in the episode, Dipper and Wendy spot it after a huge creature eats a Pitt Cola billboard from in front of it. So they head to a car dealership for a ride to the bubble, but they run into Sheriff Gideon. He tries to stop them but Wendy easily escapes Ghost-Eyes and snatches the bubble's key from Gideon's neck. After they get a ride they race Gideon and company to the bubble. When they somehow get over a gorge, Dipper convinces Gideon that the best way for him to win Mabel's heart is to let Dipper, Wendy, and Soos pass and for him to fight Bill.
In the episode "Weirdmageddon 2: Escape From Reality," Dipper, Wendy, and Soos enter the bubble. Later they figure out that the bubble includes everything Mabel wants, hence it is called "Mabeland." They try to rescue Mabel from this fantasy world and go back to reality. When Mabel finally agrees to go, Mabeland turns against her, becoming dark, and its inhabitants turn into monstrous versions of themselves. It ends up getting popped by a giant knitting needle.
The bubble is mostly bright pink, is emblazoned with a large shooting star similar to the one from Mabel's sweater, and has formed pink cracks.
Mabeland is filled with infinite energy, allowing anybody inside to receive anything they desire, sometimes even before the person knows they want it. Mabeland's appearance, therefore, is completely filled with happy, colorful, and goofy objects and characters, because the bubble was created to trap and entice Mabel specifically. Notable locations include an ice cream beach, Giggle Creek, and a large sand castle esque tower guarded by waffles that Mabel resided in.