Aquan

An Aquan world is liquid from its surface down to the core. The liquid is water inside the habitable zone, ammonia or hydrocarbon on the cold worlds, and a liquid known only by its survey designation on the rest. Everything on one floats, swims or is moored to something that does. Hull ratings are specific to one world, since the density and chemistry of the liquid change what a meter of depth costs.

Planetary environment

Crossing it

Navigate: DC 16
Forage: DC 12
Notice: DC 18

There is no landmark at any depth. Vessels navigate by inertial tracking and by beacon, and a vessel that loses its beacon is lost.

Exposure

Contaminated Atmosphere

Air that can be breathed and should not be: spore, ash, chlorine, coolant or fallout.

CON save, DC 12. End of each minute. The Poisoned condition until an hour after leaving the atmosphere.
- Filtration
  
  A rebreather or sealed suit removes the check. A filter mask gives advantage on it.
- Visibility
  
  Ash and dense spore make the area heavily obscured beyond Close range, in addition to their other effects.
- Radiological
  
  Where the contaminant is radiological, a failed save also inflicts a level of exhaustion that a long rest will not clear. It is removed by a Medicine check against the same DC, a restorative spell or a course of antiradiation drugs.
- Conversion
  
  A failure in Bloom atmosphere also counts as one day of exposure toward conversion.

In play

Depth

A vessel's depth is limited by its hull rating, since there is no bottom. Crush Pressure applies below the rating.
Liquid medium

The GM states which liquid fills the world. Fire damage is halved or negated in water. In a hydrocarbon sea fire works normally and endangers every creature, including the party.
Drift

Structures drift on the current unless they are under power. A station's charted position is valid only on the day it was charted.

Regions on it

Island Land surrounded by water on every side, where the only way off is a landing point, boat or beacon.
Oceanic Trench A subduction trench cutting miles below the sea floor, the deepest water on the world, enterable only by a trench-rated hull.
Open Ocean Water with no bottom in reach and no cover of any kind, lit at the top and twilight below.
Seamount An underwater mountain that does not reach the surface, and the one landmark in open water.
Shallows Water over the shelf with the bottom in sight, lit, crowded, and shallow enough to work in.
The Deep The water below the last light: cold, black, and the largest habitat on any water world.
Vent Field An isolated community of life on the sea floor, fed by hot vents or cold hydrocarbon seeps.