Vietnam is approximately the size of Germany with land borders to the north and west and water to the south and east. The northern part of the country is mostly hills, highlands, and the Red River Delta. The mountains are covered with dense forest and the Delta is very densely populated. To the south, the soil is very poor and so the coastal lowlands are not farmed. The forests are also less dense. The terrain in Vietnam is rough and unpredictable, an advantage used by the Viet Cong during the Vietnam War.
As the terrain varies, so does the climate. The south is tropical, and the north is monsoonal. The north has a hot rainy season from May to September and a warm dry season from October to March. Vietnam is subjected to monsoons and massive flooding on occasion. This could make for very uncomfortable elements for a soldier to face day in and day out.