Jean Hilliard’s case is remarkable, but it is not entirely without precedent in the medical and historical record.

There are other cases of survival from what appeared to be impossible hypothermia, and understanding them alongside Jean Hilliard’s story helps clarify what is and is not genuinely mysterious about extreme cold exposure.

One of the most frequently cited cases is that of Anna Bågenholm, a Norwegian skier who in 1999 became trapped under ice in a frozen stream in northern Norway.

She was submerged in ice-cold water for approximately 80 minutes, during which time her core temperature fell to approximately 56.7 degrees Fahrenheit (13.7 degrees Celsius) — one of the lowest core temperatures ever recorded in a human survivor.