At 6th level, a ninja learns to move while barely touching the surface underneath her. As a full-round action, she can move up to twice her speed, ignoring difficult terrain. While moving in this way, any surface will support her, no matter how much she weighs. This allows her to move across water, lava, or even the thinnest tree branches. She must end her move on a surface that can support her normally. She cannot move across air in this way, nor can she walk up walls or other vertical surfaces. When moving in this way, she does not take damage from surfaces or hazards that react to being touched, such as lava or caltrops, nor does she need to make Acrobatics checks to avoid falling on slippery or rough surfaces. Finally, when using light steps, the ninja ignores any mechanical traps that use a location-based trigger.
Vesper Primer+Full Round Actions+Light Steps