Updated June 8th, 2019.
When you’re looking at a Finder window, and you want to climb up one level, hold the ⌘ key and type the up arrow. Up you go.
For example: let’s say you’re looking at Finder window with a bunch of icons in it. Across the top of the window it says “My Favorite Photos.” Now you’re wondering “Where is this folder called ‘My Favorite Photos’?” You could hold the ⌘ key and click on the name of the folder, in the title bar– that would show you a menu with the complete path to the window you’re looking at. But if you just want to go there, type ⌘-up arrow.
Another example: you’re somewhere in the Pictures folder, several folders deep. You want to climb up until you’re at the Pictures folder itself. Just tap ⌘-up arrow until you’re there.
See also my post “Command-Click a window’s title to show the document’s location.“