There's no hiding the fact that offshore sailing is inherently dangerous, but increasingly better training and safety systems are being employed to avert disaster. Over the past 12 months, Shirley and the CNN MainSail team have been meeting sailors from around the world and reliving their tales of survival at sea. From entries in the legendary ocean classic, the Rolex Sydney-Hobart Race, where boats have disintegrated in wild storms, to solo sailors who have been rescued in the wastelands of the Southern Ocean, these are powerful tales illustrated by footage filmed by the sailors themselves and the rescue services who risked their own lives to save others. And as boat design and construction and safety equipment and techniques improve, Shirley joins the crew of the Volvo Ocean Race round the world entry Alvimedica as they carry out survival training at the environmental pool facility in Newcastle, UK. There, Shirley finds out for herself just how disorientating an ocean rescue can be and how every second counts in the race for survival. And then she puts her own body to the test in a thermic shock tank at a naval facility in Portsmouth, UK. This edition of CNN Mainsail takes the viewer to the heart of some major ocean rescue situations and shows just how world turns upside down.