It should be more easily discoverable, but command-shift-g lets you type in the path directly, and even has tab completion. If you want to navigate visually, navigate up to the computer or drive where you want to start, then press command-shift-period in order to see all of the directories that are usually hidden.
Both of these approaches work in the open and save dialogs, and not just the Finder.
Both of these approaches work in the open and save dialogs, and not just the Finder.