I'm assuming that you would be referring to the "peak" of a mountain. The peak of the mountain is generally the tallest point; thus opposite of the base.
the oppposite OS the base of a mountain is the summit
The opposite of the base of a mountain is its peak or summit. The base of a mountain refers to the bottom or lowest point of the mountain, while the peak is the topmost point. It is the highest elevation of the mountain where the slopes converge.
The opposite of the base of a moutain would be it's peak. The very tip of the mountain where all the snow rests and where it's coldest.
an antonym for that would be at the mountains base
The antonym base of a mountain refers to the lowest point or bottom of the mountain, often called the mountain's foothill or base camp. It is the opposite of the peak or summit of the mountain, which is the highest point. The base of a mountain typically serves as a starting point for climbers or hikers to begin their ascent.
The fat end that's connected to the land, it's opposite the pointed end.
The opposite landform could be a lowland. Or in the ocean, a trench, deep or abyss. In mountains, the natural opposite of a peak is a valley. The opposite structure of a mountain, where the elevation is lower rather than higher, is a crevasse or chasm.
base of a mountain
The base of a mountain is typically referred to as the mountain's "foothill" or simply as the "base" of the mountain.
A gorge.
The base word of mountaineering is "mountain."
The Peak