The wind suddenly quieted the moment the ship entered the reefs.
Those bone-like reefs blocked most of the sea wind, enveloping the ship in an eerie calm. The sails hung limp, their driving force gone, and Nami told Usopp to furl them so they could move forward using oars and the current. Zoro and Luffy took an oar each, one on either side, rowing slowly. The hull squeezed through narrow channels between the reefs. At the tightest points, less than two meters separated it from the reef walls on either side, close enough to reach out and touch the gray-white rock.
Naruto crouched at the bow to look underwater. The water was clear, with excellent visibility, and the sunlight shone straight down, revealing the seabed more than ten meters below. He saw the bases of the reefs.
The bone shapes exposed above the surface were only the tip of the iceberg. Underwater, each "rib" connected to a thicker "vertebra," linked one after another and extending down the slope of the seabed into deeper water. They extended in the same direction as the dark red thread pointed: north by east. A dozen meters beneath the surface, fist-sized, dark silver spheres were embedded between the segments of each vertebra, forming a line that stretched from nearby all the way to the edge of visibility.
"Nami," Naruto called, pointing at the water. "There's something underwater. Little silver spheres, arranged in a regular pattern."
Nami leaned over the gunwale and peered down. After a while, her expression changed. "Those silver spheres are positioned exactly like the pattern drawn on one page of the old booklet. I couldn't make sense of that page and thought it was decorative. It turns out it was a diagram."
"A diagram of what?"
"Energy nodes." Nami stood up, pulled