The submersible had passed beneath the "base" of the City-State, where the endless dark waters replaced the vertical and rough "cliff" that had been there before. The beams of the high-powered searchlights extended infinitely in the water, within their range, nothing could be seen.
Only occasionally would there be a small flash of light within the beam, which was either floating bubbles or some "debris" that had fallen from the upper layers, reflecting the light in the water.
Duncan was turning a crank on the control panel, and the sound of water being injected in the ballast tanks changed into a low roar. He slowed down the descent of the submersible and carefully tilted it upward at an angle.
After crossing that boundary, he wanted to "look back" and observe what the base of the City-State actually looked like.
