"Hakin and Romehl!" exclaimed the girl. "Then they're safe, too!"
The tunnel walls grew rough, then disappeared. They were out in the open sea at last, although still one mile beneath the surface.
But in front of them was an angry seething school of the man-sharks, clearly illumined by the two rays of light. Behind the sharks were a score or more of serpentine steeds.
The sharks saw the two submarines and charged down upon them; but Milli, with great presence of mind, shut off her searchlight and swung sharply to the left.
"Up! Up!" urged the young man, so she turned the craft upward.
n and on they went, with no interference. Presently they turned the light on again, so as to see what progress they were making. But they were making absolutely none! They were merely standing on their tail. They had reached a height of such relatively low pressure that it took all the churning of their propeller just merely to counteract the great weight of their submarine.
Abbot switched on their chemical gas supply, and as their top fin expanded into a balloon they again began to rise.
One thing, however, perplexed the young man: the water about him seemed jet black rather than blue. They must by now be close to the surface of the sea, where at least a twilight blue should be visible. Even at the one mile depth in his bathysphere, the water had been brilliant, yet here, almost at the surface, he could see absolutely nothing.