A rock off the coast of an island whose nearest sizeable neighbour is Tristan da Cunha. Probably not one I'll be visiting in person, then.
I was browsing around the Google Maps interactive map of UNESCO World Heritage Sites after watching my wife doing a kind of virtual tour of a Czech village. I was interested in a lone dot at the south end of the mid-Atlantic ridge, which turns out to be "Gough and Inaccessible Islands", delightfully illustrated with a picture of a Northern Rockhopper Penguin. I liked the sound of Inaccessible Island (Enid Blyton missed that one), so went for a browse.
The pictures on the site are (a) copyright and (b) not labelled with location, so when I found this extraordinary image I wasn't sure even which island it belonged to. Still a little creative Googling not only allowed me to locate it as Church Rock, off the NE coast of Gough Island, but also to find the magnificent image below (from this blog), which is now (suitably cropped) installed as my desktop background.
Church Rock rocks.