Their destination is the Bubble, a niche that Goto Dengo had them carve out of the stone during the last couple of months. He claimed, to anyone who asked, that it was a water reservoir, put there to increase the deadliness of one of the traps. It is a wide vertical shaft, four meters in diameter, that begins in the ceiling of a peripheral drift and goes straight up for a few meters, then dead-ends. Ladders still cling to its walls, and by ascending, they can reach a rock ledge big enough to sit on. Canteens of water and boxes of biscuits have already been stocked here by Wing and his men.