Cold, windy days can be a nightmare when you get to camp and just want some friggin' hot chocolate before you curl up in your sleeping bag — wind and open flames often don't mix. Enter the Heatstick from Danish company Heatgear: Just shove it inside your water bottle, and in minutes you can heat water up to 194 degrees Fahrenheit from the inside. Check it:
Since it's sealed off inside the bottle, it's practically immune to wind, rain, snow, or overzealous marmots. Powered by regular camp stove gas, the Heatstick transmits heat by infrared radiation and thermal convection. It weighs just under a pound, including the bottle.
Heatgear originally developed the Heatstick for military applications. As such, it also features "unmatched stealth abilities" and "no visible thermal profile" because of its lack of flame, fits standard-issue NATO canteens, and is perfect for use "during ground-, sea- and air transport" missions.
Y'know, perfect if you regularly go camping in either Yosemite or beautiful Darfur.