This chapter follows the title of a book written some years ago by Laurence M. Gould, Chief Scientist on Admiral Richard E. Byrd's first expedition to the Antarctic. It is the most succinct way of describing the antarctic environment and perhaps the major environmental factor with which Weddell seals must cope. Under all circumstances they must maintain their body temperature at 37°C. They must do this while living in a region where the water is constant at −1.9°C. The air temperatures range from 0° to −50°C, and concomitant winds may create chill factors of −100° to −150°C.

The atmospheric conditions are usually not significant to the adult because, if the situation becomes too uncomfortable, the seal can always return to that great ameliorating agent: water. However, for the first week of life this may not be possible for the pup, and I will discuss shortly how it maintains its body temperature in a way different from that of the adult. Before discussing any of the ways in which the seals, adults or pups, regulate their body temperature, I would like to review briefly some physical characteristics of heat transfer that might help in the following discussions.