Secret Sewers

Secret Sewers is an area connected to Rubble Ruins in New Super Mario Bros. Ultra. It contains levels 2-2 through 2-. It can either be accessed through a Pipe after Cactus Cove is completed.
==Appearance==
Secret Sewers is a brown, mushy, Pipe-laden area with multiple lakes, which takes place under the upper part of Rubble Ruins. There are Piranha Plants, Jump Blocks, Munchers, and colossal stalagmites that scatter the area.
==Levels==
Level number	Level name 	Description
2-2 	Gushing Gutter 	This level is an underground level filled with Warp Pipes and Screw Platforms.
2-3 	Dripdrop Drains	This level also takes place underground, in a pipe-filled area filled with Piranha Plants and Munchers. It can be an alternate for Cascade Chasm.
2-4 	Cascade Chasm 	This level takes place in an underground chasm, as the name implies, with many Buzzy Beetles, Goombas, Pokeys, and Piranha Plants. It is additionally the first level to feature autoscrolling.
2- 	Pipeline Tower 	This level takes place in a tower with a complex system of warp pipes. The boss at the very top of the tower is Boom-Boom.