There were rocks at the base of the cliff. One of them, black and sharp, like an ugly tooth, jutted out of the water almost immediately at the side of the boat. Only Tony’s quick eye had saved them from striking against it. They had blundered into a veritable maze of reefs which extended for several yards ahead. They held their breath. It seemed impossible that they could run the gauntlet of those rocks without tearing the bottom out of the craft. But Tony’s steersmanship was marvelous. The motorboat threaded its way accurately among the jutting rocks. There was always the chance that a submerged reef might rip through the hull of the craft, but they had to take chances on that. But luck was with them. The _Napoli_ dodged the last ugly rock, and shot forward into open water. Tony sank back with a sigh of relief. “Whew, that was close!” he exclaimed. “I didn’t see those rocks until we were right on top of them. If we’d ever struck one of them we would have been goners.” The Hardy boys believed him. Angry waves dashed against the base of the cliff. They would not have lived more than a few minutes if they had been wrecked in this place. They would have been battered to pieces against the rocks. Suddenly, before them, they saw an opening in the side of the cliff. It was a long, narrow cove. The entrance was like the neck of a bottle, widening as it led into the cliff, and it was over-shadowed by jutting rocks. It had been quite invisible up to this time, and the boat had gone only a few yards further before it became invisible again, so well was the opening hidden by the rocks. “Here’s a find!” exclaimed Frank, in excitement. “Let’s turn back and see where this goes to.” Tony swung the boat around and the craft slowly made its way back toward the hidden cove. Soon the opening in the cliff came into view again. “It’s just large enough for the boat to go through,” said Tony. “Want me to try it?” Frank nodded. “Go ahead.” The nose of the boat turned toward this strange bay and then the _Napoli_ began to enter the cove. “Maybe I won’t be able to get out again,” said Tony suddenly. He looked ahead. But the passage widened into a bay of considerable extent, quite sufficient in size to enable him to turn the craft around once he had entered. So he continued. But the cove proved uninteresting. The sides were steep, although dense bushes grew about the base of the slopes, but there was no path, no trail, no indication that any human being had ever been in the place. Being protected from the wind, the water was calm. The echoes of the motorboat’s engine were flung back from every side in a roaring volume. Suddenly Frank gave a gasp of surprise! Standing among the thickets at the base of the steepest slope, was a man.