The Jungle
Is it just Shmoop, or does the jungle seem like the absolute worst place to fight a war?
Most of Platoon takes place in the jungle, and this richly symbolic landscape is full of surprises. If the NVA are the overall enemy, and the soldiers themselves the real enemy (Chris Taylor: "I can't believe we're fighting each other"), the jungle is a great candidate for other enemy. This exotic, humid place can be as unforgiving as a machine gun.
Jungle Problems
For starters, it's incredibly hot, humid, and wet. The filmmakers make sure we notice this: the guys are always sweating (their headbands are usually drenched) and it rains on several occasions (or looks like it's just gotten done raining). Fighting a war against an enemy you can't see is bad enough. Fighting that enemy in the rain (and hoping your gun doesn't get jammed from the water) is even worse.
The jungle is also dense, so dense that it often cannot be traversed without the help of a trusty machete (during Taylor's first romp in the jungle we see the guys using this tool to hack their way through the foliage). Such dense terrain makes finding and killing an almost invisible—and certainly better adapted enemy—doubly difficult.
In addition to being dense, the jungle is also full of surprises—dangerous snakes, booby traps, and hidden bunkers. The very fact that the jungle could unleash, so to speak, any number of terrifying things, makes is an especially scary place.