Dungeons & Dragons 3.5 Feat: Altitude Adaptation

Your body adapts quickly to changes in altitude, preventing you from suffering as much from altitude sickness.

Base Fortitude save bonus +2.

You gain a +4 bonus on all Fortitude saving throws to avoid the effects of altitude. Additionally, when you determine what effect the altitude has on you, you apply the effect for the next lower category of altitude than the category you are actually in. After you spend a week at a specific altitude, you become acclimated to that altitude and all lower altitudes, and no longer have to make Fortitude saving throws for each 6-hour period to avoid altitude sickness. If you travel to a lower altitude and remain there for a week, you lose your acclimation to the higher altitude and must reacclimatize, although you always retain the other benefits granted by this feat.

This feat grants a +2 bonus on all Survival checks made in high altitude (above 5,000 feet) areas.