Infographic: Ocean Worlds
Traveller referees, this is a new way to interpret the Hydrographic code of the Universal World Profile (UWP). Any Hydrographic code above zero indicates the presence of water on a world, but it doesn't say that all of that water has to be on the surface! There could be vast subterranean oceans of liquid water, even on worlds where the Atmospheric code indicates tainted or dangerous atmospheres. This could help explain why there are populated worlds with Corrosive atmospheres - the inhabitants live underground, and extract minerals from the ice or water below the surface.