Winter's Child
(Savage Species, page 40, DnD 3.0)
[General]
You are adapted to a cold environment.
Prerequisite
Cold terrain
Benefit
As an arctic dweller, you are more hardy. The DC of your Fortitude save to avoid subdual damage from cold is reduced to 10 (see Cold Dangers in Chapter 3 of the DUNGEONMASTER's Guide). In addition, you can make a saving throw each minute (DC 10, +1 for each previous check) to resist the effects of hypothermia in very cold water.