How body fat helps this elite athlete

Science doesn't fully understand how she does it, but ocean swimmer Lynne Cox survives in water that is cold enough to kill. Researchers have been trying to understand her unique ability for 30 years.

Turns out, Lynne's generous figure may be the key to her success. In her 2003 interview with Scott Pelley for 60 Minutes II, she proudly discloses her weight and even uses the word "blubber" in a conversation about her body.

If that's not remarkable enough, watch her try to swim a mile in the coldest seas on Earth. In a watery world inhabited by penguins and seals, Lynne decided to see whether she could survive swimming to Antarctica, and our film crews were there, cringing every second.