Cape Horn (South America)
The legendary landmark of round-the-world sailors, Cape Horn marks the end of the Southern Ocean.
But it needs to be treated with respect, as the ocean shelves rapidly and narrows to about 200 miles between South America and Antarctica, squeezing the weather systems and generating highly confused - and often dangerous - seas.
Once past the Cape, temperatures quickly rise and the journey home up the east coasts of Argentina and Brazil is largely upwind, although MacArthur was delayed in this area because of light winds.
The doldrums again have to be negotiated before the north-east trades and the Azores high present more upwind challenges.
Northern hemisphere winter storms as sailors approach the finish provide fast but tough sailing right to the end.