In Lord of the Flies, the mountain, obviously the highest point on the island, is, therefore, symbolic of the pinnacle of life. The boys place their fire atop it, but this fire goes out and is stolen by Jack and the other hunters. Simon and Ralph and Jack and Roger climb up, fighting the snake-like creepers in order to discover exactly what it is that looms in the air over this mountain, but Simon is killed when he brings his message that the beast is within them all. Releasing a huge pink granite "death rock," the stone--"that token of preposterous time"--from near the top the mountain, Roger sends Piggy reeling to his death.
Thus, the mountain can be seen as the pinnacle of life and civilization, a pinnacle that the boys are prevented from reaching by the nature of the flaws that are inherent in their characters, flaws from which there is no escape.
The interpretation of the mountain's significance in "Lord of the Flies" is much simpler than the other symbolic representations in the book. The Mountain represents hope and truth. Hope in that they boys believe that by building a signal fire on top of the mountain, they will be rescued. Truth in that, like moses climbing the mountain to receive the truth of the ten commandments, Simon climbs the mountain to gain truth of the Beast. The mountain symbolizes truth also because in truth is knowledge. By utilizing their vantage point atop the mountain, the boys can see the "truth" of their environment and their situation.