The image is iconic: a tightly tethered helmsman, white knuckles on the windward steering wheel, as the bow of his carbon-fiber Volvo Ocean 65 racing sailboat pierces the backside of a massive Southern Ocean wave. A wall of green water roars back at the on-watch crew, and the helmsman battles to maintain steerage. He rivets his attention on the electronic displays, never daring to glance astern. Then, just as gravity returns to a wildly stressful situation, the boat’s stern lifts and the sleigh ride commences anew, resubmerging man, machine and marine electronics into a saltwater bath that’s barely above freezing. Simply surviving here is risky business, but to engage the Southern Ocean as part of the infamous Volvo Ocean Race, where all skippers routinely push their boats, crews and equipment to near breaking points, is the marine world’s ultimate acid test.