The shift from the dry, razor-thin gales of Vault 4 into the underground transit aqueduct was like stepping through an upright waterfall into an upside-down ocean.
The turquoise water didn’t fall into the deep gap. It surged upward against the Earth’s gravity. It was drawn by the huge tidal pull of the mantle’s hydro-moving nodes. The channel was a tube-shaped tunnel forty meters in width, carved from a single seamless tube of blue lapis lazuli and iron-hard metal. It spiraled downward at a steep forty-five-degree pitch toward the oceanic floor of Vault 5.
Arthur Vance drifted inside Echo’s spatial boundary field, his hands steady on the steering harness of his diving rig.
Around them, the water was a glowing, swirling vortex of liquid crystal. It carried no settled mud, no salt crust, and no sulfur ash. It was ancient, uncorrupted ancient salt water, preserved since the world-size crust first cooled four billion years ago. The surrounding light was a soft, rhythmic pulse of deep azure that shone off the rainbow-bright scales forming along Echo’s flanks.
Echo was in his total element.
The three-meter salamander was no longer the sluggish, dry-skinned creature that had flopped across the flat stone slabs of Vault 4. In this clean aether-rich water, Echo’s external cyan gills swelled until they looked like weeping willows of spun turquoise silk, fluttering with rapid, thrilled beats. His paddle-like tail drove through the counter-current with easy power, his water-flow mucus lubricating the water column so smoothly that the entire squad…
