KATE UPTON suffered frostbite while shooting her 'Sports Illustrated' Swimsuit Issue spread in Antarctica. She says, 'When I came back, I [temporarily lost my] hearing and eyesight. Because my body was shutting down, working so hard to keep me warm.'

So what gave her the strength to carry on? The PENGUINS. She said, 'The penguins kept me going! They're adorable. Anytime I was like, 'I can't do it anymore, I can't do it!' I would look at them and I was like, 'Okay, for them . . . '"

Kate was actually the ONLY model "SI" took to Antarctica and in a twist for the modeling industry, she was chosen because she's NOT skinny.  The editor of the Swimsuit Issue says, 'I knew if I needed to bury someone in clothing [because of the cold], I needed her physique and curves to come through. So to bring her was obvious: I knew I could put a one-piece on her and she wouldn't look flat, she'd still look voluptuous and healthy and shapely and sexy.'

No wonder she had frostbite.  At least in the cover shot she had on a jacket.