The "oceanic pole of inaccessibility." If you want to be really, really alone, head for 48°52.6′S 123°23.6′W in the South Pacific Ocean. That's "Point Nemo," the point in the ocean farthest from any land. You'll be in the middle of 22,405,411 square kilometers of ocean, an area larger than the entire former Soviet Union.
Never been there.
Its twin, the point on land farthest from any ocean, is at 46°16.8′N 86°40.2′E, outside the Chinese city of Urumqi, in the Dzoosotoyn Elisen Desert. It's 1,645 miles from the nearest coastline.
Never been there either...and not on any fancied future itinerary--you can count on it!