This was a large affair, being at least forty feet wide and high, and several hundred feet long. "Now, if only Bob were safe, all would be well," thought the young diver. Without waiting to light another torch he began to move toward the outer opening of the cave. But before he had gone half the distance he came to a halt with a cry of dismay. The cave was crossed by another underground stream, all of twenty feet wide, and flowing onward with tremendous swiftness. It came out from under one rocky wall and disappeared under the wall opposite. Taking a bit of driftwood, Dave threw it into the water, and it flashed out of sight instantly. "I can't swim across that," he thought, dismally. "To attempt it would be foolhardy." Now what was to be done? He examined the walls carefully. They were perfectly smooth, thus affording hold for neither foot nor hand. "If the stream weren't quite so wide I might jump it," he reasoned. "But I--somebody is coming!" He was right; somebody was entering the cave from the outer end. The newcomers were two men, one dressed in the suit of an American business man and the other in the garb of a sailor. "We'll be alone here and can talk the matter over without fear of interruption," said one of the pair, the man in ordinary clothes. His voice sounded strangely familiar, and Dave strained his eyes to catch a better sight of him and of his companion. Then, astonished beyond measure, the young diver dropped out of sight behind a rock bordering the underground stream he had been trying to cross. The newcomers were Lemuel Hankers, the man who had set sail in the _Raven_ after the sunken treasure, and Pete Rackley, the rascal who in Washington had accused Dave of robbing him! CHAPTER X DAVE OVERHEARS A PLOT "They are here for no good purpose!" Such was the thought which crossed Dave's mind immediately after making his astonishing discovery. As much as he wished to be saved from his present direful situation, he resolved to keep his presence a secret. These men were his enemies, and by instinct he felt that Pete Rackley must be Lemuel Hankers' tool. "I'll wager old Hankers had him try that game on me in Washington," thought the young diver. "It was done so that I couldn't join the _Swallow_ at San Francisco, and that father might remain behind, too, to get me out of the scrape." Presently Lemuel Hankers and Pete Rackley came so close that Dave could hear all that was said with ease. "It is a surprise to me that the _Swallow_ stopped here," Lemuel Hankers was saying. "Do you think she was following us?" "Can't say as to that," replied Rackley, puffing away at a short pipe he was carrying. "Anyway, she's here. Now what is your game? Out with it." "The game is that I don't want the Fearlesses to get at the sunken treasure, Pete." "I've heard that before, Lemuel."