After a three-day delay to avoid the worst of Cyclone Pam, the six-boat Volvo Ocean Race fleet has now set out from Auckland, New Zealand, for Leg 5 through the Southern Ocean.

Although the competition couldn’t be tighter, with a tie for first place overall between Abu Dhabi Ocean Racing and Dongfeng Race Team, the fleet has yet to be tested by any kind of prolonged rough conditions. However, all that is going to change in the course of this grueling 6,770-mile marathon to Itajaí, Brazil, via Cape Horn—what is in many ways the defining leg of the entire race.

According to VOR meteorologist, Gonzalo Infante, “The conditions will be light early on, with coastal sailing up to East Cape at the tip of New Zealand, but after a few days it will be the full-on Southern Ocean regime.” From then, he says, “The boats will be facing 25-35 knots of wind for much of the time until they round Cape Horn.”

Of course, this being the Southern Ocean, the fleet will also find itself dealing with finger-numbing cold, the threat of icebergs and the sometimes monstrous waves that result as the prevailing westerlies and low-pressure systems that define this part of the world march unimpeded around the South Pole.

Not surprisingly, these kinds of boat-breaking conditions and the toll they take on their crews could create havoc in the leader board. In the words of Abu Dhabi navigator Simon Fisher: “There’s nowhere else on earth where you can do so much fast downwind sailing for so long. It’s going to be the first time the whole fleet sees a lot of wind for an extended period and it might shuffle the pack. Keeping in one piece all the way to the Horn is important, because that’s where the race will be won and lost.”

As evidence, race fans need look no further back than the 2011-12 VOR, when Leg 5 winner Puma Ocean Racing and skipper Ken Read were the only ones in the six-boat fleet to escape serious damage, and eventual overall winner Groupama found itself limping over the finish line under jury rig.

Still, for the sailors themselves, they wouldn’t want it any other way. In the words of six-time race veteran Stu Bannatyne of New Zealand, recruited by Team Alvimedica and U.S. skipper Charlie Enright to help show the rest of the crew the way around: “This is the best sailing in the world.”

“We are excited to get there,” agreed Enright, a little more cautiously on the eve of the start, “but there are a lot of unknowns between here and Brazil. We will experience a lot of heavy air downwind sailing which we seemed to be pretty good at leaving Cape Town, but the priority is to keep the boat and the crew in one piece.”

The boats are expected to arrive in Itajaí around April 7. We’ll see what kind of shape Enright and the rest of the fleet are in when they’re in when they get there. One things for sure, by the time they do, they will have all had a heck of an adventure.