You let the house go.

Or you keep the little extra, which is the same story with smaller handwriting. Air expands as the mountain of water shortens. Expansion makes more lift. More lift shortens the mountain faster. The whiteboard was always this mean.

Nereid rises like a thought you cannot take back. Ears pop. The moon pool tries to become a fountain and then a problem for the lock. TIDE lists depths that used to be yours: eight hundred, six, four. Yuna’s map is a postcard of somewhere you left.

Surface weather hits the hull with a sound like gravel in a drum. Gannet yells on radio, parents in a storm, no crane, no miracle. You live. The habitat lives in the way a patient lives. The vent field, Paz, the samples, the job—those stay down with the mountain.

Vargas makes you write it before anyone sleeps: Positive buoyancy can run away. A habitat is not an elevator. Seeing the sky is not a search.

You look out a port and finally have a view: gray water, ugly waves, a sky that does not care. It is a terrible prize.

THE END

What you learned: air in tanks expands as pressure drops, and extra lift makes more extra lift. Uncontrolled ascent is not a shortcut. The habitat sits on the terrace on purpose.