2. Sleep with one eye open The Southern Ocean is home to vast, pristine icebergs – and with up to 90% of their mass submerged underwater, they really pose a formidable danger for Volvo Ocean Race sailors. That's why Race organisers have added and Antarctic Ice Exclusion Zone into the Leg 3 sailing instructions. Despite this, the sailors still have to remain vigilant and on the look out, particularly for the but smaller, drifting growlers, which are harder to spot. The worst part? When the black of night comes, they still lurk – silently waiting.