Jungle boots are a type of combat boot designed for use in jungle warfare or in hot, wet, and humid environments where a standard leather combat boot would be uncomfortable or unsuitable to wear. Jungle boots have vent holes in the instep and sometimes a canvas upper to aid in ventilation and drainage of moisture. Development and use The use of "jungle" or "hot weather" boots predates World War II, when small units of U.S. soldiers in Panama were issued rubber-soled, canvas-upper boots for testing. Developed in conjunction with the U.S. Rubber Company, a pair of jungle boots weighed approximately three pounds. Adopted in 1942, the design of the jungle boot was based on the idea that no boot could possibly keep out water and still provide sufficient ventilation to the feet in a jungle or swamp environment. Instead, the jungle boot was designed to permit water and perspiration to drain, drying the feet while preventing the entry of insects, mud, or sand. In 1942, fused layers of original-specification Saran or PVDC were used to make woven mesh ventilating insoles for newly developed jungle boots made of rubber and canvas. The Saran ventilating insoles trapped air which was circulated throughout the interior of the boot during the act of walking; moist interior air was exchanged for outside air via the boot's water drain eyelets. In cold weather, the trapped air in Saran insoles kept feet from freezing by insulating them from the frozen ground; when walking, the insoles circulated moist air that would otherwise condense and freeze, causing trench foot or frostbite. The new M-1942 canvas-and-rubber jungle boots with Saran mesh insoles were tested by experimental Army units in jungle exercises in Panama, Venezuela, and other countries, where they were found to increase the flow of dry outside air to the insole and base of the foot, reducing blisters and tropical ulcers. The Saran ventilating mesh insole was also used in the M-1945 tropical combat boot. World War II Positive reports from users in the Panama Experimental Platoon on the new lightweight footwear led to M-1942 jungle boots used by U.S. military personnel in tropical/jungle environments, including U.S. Army personnel in New Guinea and the Philippines, and in Burma with Merrill's Marauders, the 1st Air Commando Group and the Mars Task Force (5332nd Brigade, Provisional). This style footwear wore faster than the standard Army Type II field shoes, so they