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Diving & habitats
The diving physics referenced throughout the archive are real-world tiers. They are the one place this site does not invent. Everything else stands on top of them.
The depth tiers below are canonical to ocean engineering and to this archive. They are not adjusted for narrative effect. A claim about what a human can do at a given depth must respect the corresponding tier; if a fictional habitat sits at six hundred metres, it is reachable only by ADS or submersible, full stop.
The tiers exist because pressure and gas chemistry impose them. Saturation diving solves the gas-loading problem at the cost of confinement; ADS solves the pressure problem at the cost of articulation; submersibles solve both at the cost of putting a hull between the diver and the water. There is no fourth answer.
The tiers
| Range | Tier | Notes |
|---|---|---|
| 0 m – 30 m | Recreational SCUBA | Single-tank air, ~1 hour bottom time. |
| 30 m – 100 m | Technical / mixed gas | Decompression mandatory; trimix at the deep end. |
| 100 m – 300 m | Saturation diving | Heliox; days to weeks of pressurised confinement in habitat. |
| 300 m – 700 m | ADS & saturation specialty | Atmospheric diving suits keep the occupant at 1 atm. |
| 700 m – 6,000 m | Crewed submersibles | Pressure-hull only; the diver never contacts water. |
| 6,000 m – 11,000 m | Hadal — DSV expedition | Rare; trench bottoms reachable only by purpose-built DSVs. |
Zoological zones
A separate axis: where life is, not where humans go. The zones are used in species and place copy when the question is what kind of light, current, or pressure regime an organism inhabits.
| 0 – 200 m | The Lighted Surface | Sunlit upper water; storms and ships pass through it. |
| 200 – 1,000 m | The Sunlit Reach | Photic floor to first dim; kelp canopies and the shelf break. |
| 1,000 – 4,000 m | The Twilight Belt | Mesopelagic to bathyal; bioluminescence common, sunlight gone. |
| 4,000 – 8,000 m | The Midnight Zone | Lower bathyal to abyssal; trench floors, vent fields, the Pelagine seats. |
| 8,000+ m | The Abyssal Plain | Hadal depths; sparse, slow, almost without us. |
Equipment & systems
diving · 300 – 700 m
ADS — the Newtsuit lineage
The articulated atmospheric diving suits used by the survey from roughly three hundred to seven hundred metres.
communications · surface – 4 000 m
Hydrophone networks
The passive listening grids that monitor the human shelf and the bathyal approaches; not surveillance, exactly, but the closest the survey has.
diving · 100 – 300 m
Saturation diving systems
The pressurised-confinement protocol used by long-duration human work between roughly one hundred and three hundred metres.
submersible · 700 – 11 000 m
The DSV class hierarchy
A three-tier classification of crewed submersibles by depth rating, used by the survey for tasking, insurance, and crew certification.
surface link · 0 – 600 m
The Helmsward cable
A single fibre-and-power conduit running from the surface link down to Varangurd and on along the shelf to the deeper enclaves.