(Double points leg)

Leg 3 of the race from Cape Town to Itajaí, Brazil takes the fleet on a monstrous 12,750-nautical mile (14,672-mile/23,613-kilometre) Southern Ocean passage three quarters of the way around the bottom of the world.

The Southern Ocean – also known as the Antarctic Ocean, South Polar Ocean, Austral Ocean – is the world’s wildest and most remote expanse of open ocean. It begins at latitude 60° south and encircles the Earth’s southernmost continent, the ice-enshrined landmass of Antarctica.

Conquering these almost mythical, southernmost waters of the planet has long been a badge of honour for the world’s best sailors.

On the way from Cape Town to Itajaí the crews will pass far south of the world’s three Great Capes: The Cape of Good Hope close to the tip of Africa; Cape Leeuwin Australia’s most south-westerly point; and the notorious Cape Horn on Hornos Island – the most southerly headland on the Tierra del Fuego archipelago of southern Chile. It is impossible to overestimate the significance of this leg – the longest in the race’s history – or the challenge it poses for the sailors taking it on. The route is expected to take around 34 days to complete – by far the longest time spent down in the storm-ridden icy wilderness of the Southern Ocean in any previous edition.

Appropriately then, the leg counts double in terms of points – with the first set of points awarded for the order the boats pass longitude 143º East (close to the western coast of Tasmania) and the second set for the finishing order in Itajaí. After negotiating their way out of Table Bay the fleet will head south past South Africa’s Cape of Good Hope where they will likely spend a bumpy first night courtesy of the tumultuous waves thrown up by the Agulhas Current which weaves its way around Cape Agulhas – the southernmost tip of Africa. The further south the teams dive the shorter the route around the bottom of the world, where water temperatures range from -2 to 10°C. In early editions of the race, crews would get as close as they dared to Antarctica in an effort to shave virtual distance off their route. This strategy meant racing through ice floes – a precarious and at times terrifying experience for the sailors.

These days, because the modern boats are nearly three times as fast and a collision with even a small piece of ice could be catastrophic, a virtual exclusion zone is imposed by the race committee to keep the fleet north of the ice zone. The areas from 40 degrees south to the Antarctic Circle are known as the Roaring Forties and the Furious Fifties – have the strongest average winds found anywhere on earth. Wind speeds generated by the cyclonic storms that surge eastward through the area can reach up to 70 knots. The teams will aim to position themselves in-front of one of these fast-moving storm fronts in order to slingshot them eastwards towards Cape Horn, the rocky outcrop at the southern tip of Chile which marks their exit point from the Southern Ocean. When hitching a ride like this the goal is to ride the storm for as long as possible. That means day after day, week after week, of dealing with screaming winds and massive white topped rolling waves. The colder the temperature, the denser the air becomes.

This in turn makes the winds stronger and more powerful. It is not an easy variable to quantify but it is one of the reasons The Ocean Race yachts often outperform their predicted speeds in this part of the world. It’s high-speed, high-adrenaline sailing that cannot be experienced anywhere else. It is what many of the sailors crave to experience first hand, but it is also tough on the crews – both mentally and physically.

Nobody comes out of the Southern Ocean without being changed in some way by the experience. As a gauge of just how remote this area of the planet is, during Leg 3 the fleet will pass close to Point Nemo – coordinates: 48°52.6′S 123°23.6′W – which, at 1,670 miles (2,688 kilometres) from the nearest piece of land, is officially the most remote spot on the planet. So remote in fact that the closest human beings to the sailors are the astronauts in the International Space Station, orbiting the world 250 miles (400 kilometres) above them. Two Maritime Rescue Coordination Centres (MRCC) cover this area. The New Zealand centre is responsible for the waters west of longitude 131°, while the waters east of that line are monitored by a centre in Chile. Staff at The Ocean Race headquarters in Alicante track the competing yachts around the clock and are in constant contact with the two MRCCs.

Despite making up just 30 per cent of the world’s oceans, the southern ocean plays a critical role in our planet’s delicately balanced climate system. The waters in the region absorb around 60 to 90 percent of the heat that transferred to the seas in the last 15 years, and about 40 percent of the human made carbon dioxide. Worryingly, the Southern Ocean is warming more rapidly than any of the other oceans and its ability to capture CO₂ is expected to reduce gradually over time. This would mean more CO₂ in the atmosphere and will accelerate climate change.

This warming, along with the effects of acidification, fishing, and micro plastic pollution has sent the Krill populations in the region into a decline. Krill are a keystone species and the main food for the majority of marine predators like penguins, seals, whales, and fish – the numbers of which are predicted to also decline. The region’s harsh prevailing conditions and extreme remoteness means that few scientific research vessels visit the area and as a result there is still a huge amount that is unknown about the Southern Ocean.

The Ocean Race is helping to address that problem by providing valuable data to ocean research organisations about the state of the Southern Ocean waters. This invaluable data – including oxygen levels, water temperatures, and levels of microplastic pollution – is gathered by the crews as they race through the deep south. It is hoped that this input will result in a better understanding of the Southern Ocean and allow scientists to make more accurate predictions and projections about the region and its role in the global ocean and the world’s climate, leading in turn to governments and other key organisations being able to make better policy decisions about how to protect and restore our oceans. Racing through the Southern Ocean is a knife edge balancing act between your performance relative to the other teams and survival. Sail too cautiously and the fleet will leave you behind, but pushing too hard can result in broken equipment – or worse. Lives have been lost in the Southern Ocean on previous editions of the race.

To exit the Southern Ocean the teams will eventually need to head north to round Cape Horn – the southernmost piece of land on the planet. It is a legendary part of the world in seafaring terms and infamous throughout the ages for shipwrecks and sinkings. Rounding Cape Horn is a seminal moment in an ocean racer’s life and an experience sailors never forget. The lucky teams who round the Horn in daylight and in good weather may catch sight of the small, rather inauspicious, rocky islet. Those rounding at night must make do with a glimpse of the lighthouse on Hornos Island or, in bad weather, not see ocean racing’s most famous landmark at all. Rounding the Horn will be a major milestone on Leg 3 but there are still plenty of challenges for the crews to face before they cross the finish line in Itajaí.

After clearing Cape Horn the fleet first heads north along the coast of Argentina where the predominantly squally conditions have resulted in equipment failures and even dismastings.

Based on the weather forecasts the teams must choose which side to pass the Falkland Islands, before making their way along the coast of Uruguay and Brazil towards the finish line off the mouth of the Itajaí-Açu River which leads to the city of Itajaí.