When a Dired buffer lists subdirectories, you can use the page motion commands C-x [ and C-x ] to move by entire directories (see Pages).
The following commands move across, up and down in the tree of directories within one Dired buffer. They move to directory header lines, which are the lines that give a directory's name, at the beginning of the directory's contents.
dired-prev-dirline). These lines are the ones that describe a directory as a file in its parent directory.