In which Ida discovers new ways to walk
Chapter IV: Water Palace is the fourth level of Monument Valley. Ida first experiences walking on the side of monuments.
The level takes place in several pink areas atop a lake with Lilly pads. When each area is completed, the environment creates a way for Ida to travel to the next one. At one point, Ida is turned sideways, introducing the mechanic of walking on walls.
After leaving the Storyteller's cave, Ida solves a simple puzzle and completes the level.