They returned to the camp in the boat, following the shore inside the reef, and the three prisoners were placed under lock and key in one of the _Titania's_ cabins, the crew taking turns to keep watch outside the door to prevent any attempt to escape. Next morning Villiers volunteered to descend to the wreck and ascertain the state of the hull after the explosion. Since the guide-rope had been severed, the captured boat was pressed into service and moored as close as possible, going by cross-bearings, to the spot where the lighting-plant had been stationed. Since the latter had been destroyed, Villiers had to rely upon his portable electric lamp. The depth to which he descended before his feet touched the bottom surprised him. It was greater than he had previously worked in, and no natural light penetrated the dark waters. At first he fancied he was in a submarine forest. Gaunt ribs, distorted in the rays of the lamp, reared themselves on either hand. Closer examination showed that they were not metal but timber, badly eaten by worms, and thickly encrusted with barnacles. His foot catching in some obstacle caused him to throw the light of the lamp upon the ground. He was standing on a bed of coral on which lay dark shapes in hundreds, like a cart load of bricks dumped on the ground. "By Jove!" he exclaimed to himself. "I've come to the wrong shop. This must be the wooden hulk Swaine spoke about. She must have had lead pigs for ballast. Even that lot's worth a fortune at the present-day price for lead." Hardly knowing why he did so, Villiers lashed one of the pigs of ballast to his shot-rope, then, paying out his distance-line as he went, he made for his real objective--the wreck of the _Fusi Yama_. When that vessel's bilge loomed through the water, Villiers found that he was close to the starboard bow. Much of the steelwork had been stripped of its thick covering of weed and barnacles by the force of the explosion, but of actual damage done to the hull there was none. By a rare slice of good luck, as far as Harborough and his companions were concerned, Strauss had miscalculated the distance and direction of the wreck of the _Fusi Yama_ from shore, and had deposited the explosive charges against the side of the old wooden wreck in the belief that it was the other. The remainder of the gold was still intact. Von Giespert had shot his last bolt, and the missile had gone wide of the mark. CHAPTER XXIX A Frustrated Escape Having made this satisfying discovery, Villiers returned to the surface and reported the good news.