"Dry up!" cautioned Denbigh under his breath. "Wish I could," retorted the irrepressible Irishman. "Sure I'm wet altogether." They swam side by side, making use of the "dog-stroke", as there was less risk of attracting attention by an involuntary splashing. It was a nerve-racking ordeal, for the darkness was now intense. Hippopotami were noisy not so very far off; there was imminent danger from crocodiles, that, floating like logs in the water, were practically invisible until one was almost within arm's length of them. But on top of these unpleasant possibilities, the haunting dread that the rope ladder might have been removed was uppermost in Denbigh's mind. As the swimmers approached mid-stream, they found there was still a strong current. It was indeed a hard struggle to make the ship. Well-nigh exhausted, the two chums gained their goal. Thank heaven the end of the ladder was still trailing in the water. For some minutes the subs contented themselves by hanging on to the ropes and regaining their breath. Then Denbigh, assuring himself that the key to the cabin was still hanging from a cord round his neck, began to ascend. When his head was level with the bulwarks he peered cautiously along the deck. He could see or hear no one. Had a sentry been standing for'ard, it would have been possible to discern his outlines against the gloom. He would have much rather seen the fellow and made arrangements accordingly, than to be in ignorance of where the sentry was, since it was unlikely that all the watch on deck were skulking. Denbigh ascended another rung and waited again. This time he heard voices speaking in low guttural tones. The watch were sheltering in the fore-peak. Reassured on this point, the sub leapt lightly over the rail. As he did so his bare feet came in contact with something soft. He had pitched fairly upon a fat German, who, heedless of the risk of sleeping in the open air, had coiled himself up under the lee of the bulwarks. The shock threw Denbigh to the deck. Quickly regaining his feet, he saw the astonished German struggling to rise. Before he could do so the sub dealt him a powerful left-hander. Missing the point of the Teuton's chin, Denbigh's clenched fist struck him heavily on the nose. Thoroughly scared by the apparition of a stalwart black, the man took to his heels. Yelling with fear, his cries for assistance were rendered indistinguishable owing to the fact that he held both hands pressed tightly over his nose, which was leaving a purple trail on the deck. "Come on!" hissed Denbigh to his chum. O'Hara needed no second bidding. Clearing the bulwarks, he quickly cut adrift the ladder and raced after Denbigh, who was making with all possible dispatch for the companion. For a brief instant Denbigh fumbled with the key; then inserting it in the lock he threw open the door.