A porpoise slipped away from the _Mirabelle_ and moved this way and that to get its bearings. Then the mass of the reef to the left and the hidden shelf of a second but obscured underwater reef to the right made dark patches in the phosphorescence. Far below lay the ghostly spread of sand, and the porpoise nosed its way forward. The channel to the cove proved to be some five hundred yards long, and it seemed no time before the porpoise passed from the shadow of the trees at the shore into the starlit cup of the cove. Taking a turn about in the enjoyment of flipping its fins and giving a leap or two, the big fish then went back toward where the _Mirabelle_ hung suspended on the glassy sea. A boy it was that pulled himself up hand over hand along the anchor rope and stood dripping sea water on the bridge before Captain Blizzard. "I've found the channel, sir," he said, abruptly conscious of his importance from the admiring way in which Amos was staring at him. "There's a dangerous shelf of coral that juts out on the port side--if you let me go first, and the men man the boats and row her in, I think we shall do it safely even in this light." Captain Blizzard looked at him, his expression both serious and trusting. "Well lad, we do what we must, and you and I understand one another. Ahoy there!" he roared down to the shadowy decks from which the black spikes of masts rose high to break the sky. "Man the boats! We shall tow the _Mirabelle_ to cover, for there's a channel here!" [Illustration] He turned to Chris as the sound of running feet and of the boats being hoisted overboard came loudly in the stillness of the night. "Now Christopher, my boy, do you go down and go over the side again, and remember what we spoke of a few hours agone!" The next half-hour was an exhausting one for poor Chris. It was an impossibility for him to keep for long at a time, either his own, or the shape of the porpoise. He had to enter the water under the eyes of the sailors waiting with their oars poised above the sea, in the shape they knew; Christopher Mason. But once he dived under, in order to seek out the treacherous channel in the half-light, he needed his fish's eyes and senses. He therefore would swim a few yards as a fish, but had to surface again as himself in order to let the men see him, and call: "The length of two boats, keeping to starboard, boys. Then ease her over this way--to port." So it went, almost foot by foot until the _Mirabelle_ was safe inside the cove and turned broadside to the entrance. Then, and only then, with the anchor safely dropped to the white sandy depths of this hidden harbor, did Chris, tired to his very bones, climb up the ladder and over the ship's side. There remained the camouflaging of the _Mirabelle_, for the stars were fading and before long, dawn would banish secrecy. [Illustration]