360 m – 410 m · contested

Marker IX (Liminal Threshold)

One of nine designated meeting stations in the contested band between three and five hundred metres, used for formal Pelagine–human contact.

Marker IX is the first place I learned that a meeting can be a piece of furniture. The dome makes no pretence about its constraint — two halves, one pane, two metres of water — and the honesty of that is what makes the rest of the protocol bearable. I have arrived here on a six-day saturation schedule and left with a quarter-hour of conversation, and on every occasion the asymmetry has been a feature.

Marker IX is the third-most-active of the liminal stations. It sits at three hundred eighty metres, well below recreational reach and close to the lower limit of sustained human saturation work. From the human side it is the longest commute on the calendar: a sealed lift from Varangurd, two days of saturation pre-conditioning, an hour at the marker, then days of decompression home.

From the Pelagine side it is also the longest commute. Three hundred eighty metres is high enough above their natural pressure that prolonged stays produce genuine physiological harm; envoys are rotated within hours.

Use

Treaty signatures, audits, and quarterly courtesies.
Disputes (rare).
Material exchange — by physical hand-off in the central chamber, never by submersible drop.

Form

A neutral, low-illuminated dome of polymer and ceramic, one human-pressure half and one ambient-pressure half divided by a vertical observation pane. The two halves are never fluidly joined. Conversation is by radio across two metres of water.

The realism note here is not invented: at three hundred eighty metres a human in a saturation suit and a Pelagine envoy genuinely cannot share an air-water interface. The dome is a piece of furniture honest about its constraint.

An hour at the marker, days of decompression home. The arithmetic decides who is and is not admissible to the room, and the room is never larger than the arithmetic.