Outline mode provides special motion commands that move backward and forward to heading lines.
Move point to the next visible heading line
Move point to the previous visible heading line
Move point to the next visible heading line at the same level
as the one point is on (
Move point to the previous visible heading line at the same level
Move point up to a lower-level (more inclusive) visible heading line
All of the above commands accept numeric arguments as repeat counts. For example, C-c C-f, when given an argument, moves forward that many visible heading lines on the same level, and C-c C-u with an argument moves out of that many nested levels.