Pale translucent grass growing even as it dies.
A forced meander slows the river in a curl. The water drops organics. Soil, seeds, chemicals and eggs. NITRATES. Nutrient-rich mulch covered in pale, dying, sunless hypercharged plants. This soil hurts, it writhes with biting life. As valuable, dangerous and desired as a middle eastern oil field.
Upwards waterfall of boiling acid Vog. Encrusted with skeletons.
The river plunges into a sulphurous lava pit, evaporates and boils directly up. Condenses on the rotting roof, drips down and re-forms. Bones everywhere, anything caught within dies. Handy if you need bones. Surrounded with sulphurous mists. The most gothic thing ever.
Climbable doughnut of toxic shards.
A helix of crystals and toxic rocks around a smoking pit of chemical fire. Like a passable cage of dripping blades. Climbable and poisonous. Roof is full of chemo-maggot ratholes, crystals are piled like a snakeskin shucked off in a narrow gap.
GROTTO OF THE FARIES
Natural gasses douse your lights.
Squat globular cave hanging in its entry points like a ball in a cats cradle of tubes. No speleothems. Ways in and out lead up. The invisible gasses collecting here douse all burning flames and kill you slow. Temperature gradient gives the clue, cold air near ground may permit a spark.
Crammed with crazed giant helictites
They spiral like drinking straws left near a high heat. Flows of strange viscosity inside. Must be climbed through like mad monkey bars. Ignoring gravity, an empty space in the topographic core. Like a calcite jungle with weird fluids oozing from the tips.