The signal fire, burning on the mountain and later the beach, serves as a beacon of hope for rescue, reflecting the boys' connection to civilization. Initially, its maintenance signifies their desire to return to society. However, as the fire dwindles or extinguishes, it reveals their growing acceptance of their savage existence on the island. The signal fire acts as a gauge of the remaining civilized instincts among the boys. Ironically, a ship arrives at the end, but not due to the signal fire.