Cape Horn (South America)
The mythical 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 seas.
Once past the Cape, the journey home up the east coasts of Argentina and Brazil is largely upwind, with quickly rising temperatures.
The doldrums again have to be negotiated before the north-east trades and the Azores high present more upwind challenges.
The boats will be open to the worst of the northern hemisphere winter storms as they near the finish sometime in February.