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If you want to navigate websites with the keyboard you can make use of the 'search feature (aka "quick find for links") in Firefox. Just press' and start typing. Any link with the anchor text you type will get highlighted. Once you press enter, firefox will navigate to the link under the highlighted anchor text.
Too bad most websites nowadays don't use links for navigation and actions. They have buttons and divs and once you click them stuff happens.
And here lies the limitation with the other two build-in find features. Though the / (quick find) and the ctrl+f (find in page) search will highlight any text (not just links), nothing will happen if you press enter on that highlighted text (once you dismissed the search dialog with escape).