The boiling point of water is lower but there are a few other things going on: Most water is snow or ice so you need to raise it from that point not room tempe

The boiling point of water is lower but there are a few other things going on: Most water is snow or ice so you need to raise it from that point not room temperature. Snow also has lots of air in which means it and is a really good insulator and floats so to get a pot of boiling water you need to sit there making snow balls and dropping them and waiting for them to melt then bring that water up to temperature. All of your water for drinking, cooking and cleaning comes from snow since there often isn't any liquid water. You don't need to boil all of it unless it might be contaminated (like at a crowded camp) but it takes a lot of time just to melt a water bottles worth of snow. The ambient temperature may be lower and there will be wind. You will loose a lot of heat to convection (wind blocks or cooking in a tent help). The air is thinner and lots of stoves don't get the fuel/oxygen mix they need. The boiling point of isobutane is 10F so if you are using fuel canisters and it is cold you'll need to work to warm the fuel up as well or you'll get much less power then normal (use a propane blend, keep one fuel canister in your pocket to warm it up, put it in a warm water bath while cooking, use a stove that has a preheat loop to warm cold fuel and can be used with an inverted canister). Then once you get your water up to boil it takes longer to cook things because of the lower boiling point. They say mountaineering is for people with selective memories that prevent them from recalling suffering ;)