The Cape of Good Hope is an unseen location in Blackadder II. It is based on the real-life Cape of Good Hope on the southern tip of Africa. Notoriously treacherous, the Cape was originally known as the Cape of Storms. It's dangerous reputation is such that even Sir Walter Raleigh would never attempt a voyage through it, as he believes it contains fatal storms and dragons.
In the episode Potato, Blackadder claims he will round the Cape of Good Hope in order to one-up Sir Walter Raleigh and gain favor with the Queen. In fact, Blackadder intends no such voyage, planning instead to sail to France, vacation there, and return with exotic-seeming presents. Unfortunately, to make his plan seem legitimate, Blackadder hires Captain Redbeard Rum (known as the only captain insane enough to attempt a trip through the Cape). Captain Rum, as it turns out, has no crew and does not know the way to the Cape, or even to France.