Quote from : The Son of Neptune Book

Percy glanced over. He saw the fallen giant and seemed to understand what was happening. He yelled something that was lost in the wind, probably: Go! Then he slammed Riptide into the ice at his feet. The entire glacier shuddered. Ghosts fell to their knees. Behind Percy, a wave surged up from the bay-a wall of gray water even taller than the glacier. Water shot from the chasms and crevices in the ice. As the wave hit, the back half of the camp crumbled. The entire edge of the glacier peeled away, cascading into the void-carrying buildings, ghosts, and Percy Jackson over the edge.