How to Build a Covert Fire


“Build the fire underground,” says Daniel Martensson, an instructor at the Marine Corps Mountain Warfare Training Center in the Sierra Nevada mountains. The Defense Department began construction on the high-elevation facility a year after more than 7,300 Marines died in Korea of frostbite and other cold injuries during the late fall of 1950. The go-to tactical fire Martensson teaches is called a Dakota fire hole, named after the Indigenous peoples who built small, hard-to-spot, underground fires on the windswept plains of the upper Midwest.

First, find a suitable place to dig. Look for firm soil, not too rocky or sandy; a trowel, while not strictly necessary, will make the job easier. Excavate a conical-shaped hole, wider at the bottom, that’s about 12 inches deep and 8 to 10 inches in diameter at the top. (If you’re in snow, you’ll need to dig all the way to the frozen ground, or melting snow will extinguish your fire.) “The most important thing is the proper flow of oxygen,” Martensson says. To that end, dig a second, narrower air-draw passageway. Start about 18 inches away from your first hole. With your back to the wind, start digging at an angle until you connect to the bottom of your first hole. Pile the dirt nearby, so you can quickly refill both holes if necessary to conceal evidence of your fire.

Gather a little nest of dry bark, twigs or grass. Cupping it in your hands, ignite the center of your nest and lower it gently into your larger hole. Feed it with small, dry sticks. The air vent makes for less smoke, while the narrow opening concentrates the heat, allowing you to boil water, dry clothing and warm your hands and feet while producing little visible light. “Locate yourself underneath tree boughs to help disperse the little smoke that does come out,” says Martensson, 31, who has made hundreds of Dakota fire holes, beginning long before he joined the Marines at 17. As a child in Louisiana, he learned to build such fires from his grandfather, who served in the Army. Lowland soil tends to be softer; but don’t bother digging in soggy soil where the water table is too high. Like all skills, survival skills are perishable. “If you don’t practice it,” Martensson says, “it won’t be there when you need it.”