During this race, "you will almost certainly be attacked by a brown skua, a predatory bird that feeds on penguins," says race founder Thom Gilligan. "Runners look like large penguins to them." Marathon Tours & Travel arranges a complete itinerary for participants, which includes round-trip airfare from the U.S. to Argentina, three nighs in Buenos Aires and a 10-day cruise from Ushuaia along scenic channels and passages to the Antarctic Peninsula. Book now—spots fill up a year or two in advance.