The Outline Beneath the Shallows
The boat traveled for nearly another hour on that patch of light gray water.
After entering this area, the boat maintained a steady but slow speed, as if an invisible buffer layer was supporting the hull, reducing the friction between the boat and the water to a near-gliding level. The person at the stern occasionally adjusted the direction of the rudder, but the adjustment was small, as if following a pre-marked path, requiring no frequent corrections.
Long Tian remained squatting at the bow of the boat. Every now and then, he would dip his hand into the water to feel it for a moment, then pull it out to check the amount and distribution of powder adhering to the edge of his palm. The first few times he dipped his hand in the water, the amount of powder was relatively uniform and the distribution was relatively regular; by the fourth time, he noticed that the amount of powder had decreased slightly, and the distribution had changed from a uniform spread to a locally concentrated form, as if the powder layer on the bottom of the water was thinner in some areas and thicker in others.
He stood up and walked to the middle of the cabin, taking out a roll of fish-skin paper from the old leather pouch and spreading it out on the deck. The roll contained a rough route map he had drawn from memory based on sea caves and nautical charts. The lines weren't very precise, but the key directions and turning points were marked. He squatted down beside the fish-skin paper and traced the direction of the dotted line with his fingertip, stopping about a hand's width from the end of the dotted line. That position corresponded to their current location in the sea—they hadn't yet reached the converging end of the dotted line, but the distance was steadily decreasing.
Yu Jin walked over from the stern and squatted on the other side of the fish-skin paper, looking down at it for a while. He reached out and tapped the end of the dotted line, his fingertip remaining there without retracting it. "When we were probing the water just now, the amount of powder attached decreased once and then recovered. It's like the underwater terrain is undulating in that small area, not flat."
Long Tian nodded. He rolled up the fish skin paper and put it away, then stood up and walked back to the bow of the boat. The morning light had risen to near noon, and the light gray area on the sea surface became even paler under the stronger light, gradually turning from the initial light gray to an almost white light silver, like a layer of old paint that had dried out under the long exposure to sunlight, losing its last bit of color and leaving only the light base coat. At this moment, the hull crossed an almost invisible boundary—the water temperature changed briefly again as the bow entered the new area, but the change was smaller than before, more like the trace left by a very thin layer of water as it naturally receded after being swept by the hull.
Long Tian crouched down at the bow of the boat and dipped his hand into the water. This time, his fingertips touched not powder, but a denser surface—like a stone surface covered with a thin layer of fine sand, the dark stone residue left after being washed by the water. He gently ran his fingertip along that surface; the touch was continuous and smooth, unlike the undulations of a naturally formed rock surface, more like a paved ground.
He withdrew his hand, a thin layer of fine gray powder, finer than powder, clinging to his fingertips. He examined the powder in the morning light for a moment, not rushing to determine its composition. He simply picked up an old bowl from the side of the boat, scooped out half a bowl of seawater, and rubbed some of the powder from his fingertips onto the rim of the bowl, letting it sink to the bottom. The powder didn't disperse immediately upon entering the water; instead, it gathered into a small, clearly defined clump at the bottom of the bowl, as if drawn together by some kind of gravity.
Seeing this, the man at the stern stood up from the helm and walked to the gunwale, looking down at the clump of fine powder at the bottom of the bowl. He squatted down and gently shook the rim of the bowl; the powder didn't disperse, maintaining its clump. He straightened up and glanced at the slowly approaching sea ahead. "It's not a layer of sand anymore. It's a flat, hard surface covered with a layer of fine powder, but the structure beneath it is a single, solid mass."
Long Tian poured the water from the bowl back into the sea, tapping the rim of the bowl twice against the side of the ship to dry it. He looked up ahead; the pale silver sea continued to stretch out in front of the ship, with no obvious boundary changes, but the ship's speed was decreasing very slowly, as if it was being deliberately slowed down as it approached a certain destination.
During this time, the Dragon Shadow rose slightly above the bow of the ship, and its wingspan widened slightly, as if adapting to the potentially wider space ahead. Both its heads turned forward simultaneously, all four eyes open, and a layer of continuous light shone on the vertical line on its forehead. Unlike before, this light did not extend in a specific direction, but remained in place, shining continuously, like a lit lamp stabilizing its brightness in its position before another lamp is lit.
Long Tian stood at the bow, his gaze fixed on the slowly approaching waterline. The waterline's color gradually deepened from a light silver to a grayish hue, like a uniform, progressive change in the color of the seawater at the end of a continuously spreading layer of light color. The ship slowly came to a stop at the edge of that gray waterline, as if stopped by a persistent force field at an invisible boundary. The bow rose slightly by about a hand's width before leveling off again. For a moment, the entire ship maintained a vertical alignment with the sea surface, without tilting or skidding, as if it had been stably stopped at a predetermined position.
Long Tian flipped into the water from the bow. This time, he didn't feel the impact of the temperature difference upon entering the water—the water temperature remained evenly distributed in this area, and the change from the surface to the bottom was gentler than anywhere else before. After he sank into the water, the Dragon Shadow rose from its position against his back to his side and above. After the wing membranes unfolded, the resistance in the water was much greater than in the air, but its movement remained stable, and the light from its forehead continued to provide a stable range of illumination.
Within the area covered by the illumination field, Long Tian saw the underwater scene. It was a flat stone surface covered with a thin layer of grayish-white dust, through which the dark gray stone surface underneath could be seen. The surface continued to extend at the edge of the illumination field, without any obvious boundary or seam.
He swam along the flat surface for a while. At regular intervals, the stone surface had a shallow, longitudinal groove, uniform in depth and width, as if repeatedly carved by the same tool. After swimming along one of the grooves for a distance, it narrowed and turned at a certain point—like a guided drainage channel that naturally turned in another direction after following a fixed path for a while. He continued swimming along that turned groove for a short distance, and after extending for about two zhang (approximately 6.6 meters), the channel merged into a wider main channel. The direction of the main channel matched the angle of the wall he had passed earlier, like a carefully designed layout.
Long Tian surfaced to catch his breath. As he climbed aboard, he didn't wring out his clothes as hastily as before. Instead, he squatted by the gunwale, wiping the water from his face, and turned to the person at the stern, saying, "Underneath is a flat stone slab, much larger than that wall before. There are drainage channels on the slab, their direction mirroring the angle of that wall, like different parts of the same structure. The door has a corresponding exit somewhere underneath—not just the crack in the wall, but an even larger passageway, covered by the main channel, like a structure that has remained in place after a long period of concealment." As he spoke, water dripped from his fingers along the gunwale, the droplets making a continuous dripping sound on the deck.