Crystalline Supersaturation
This 60-foot long tunnel is filled with water (which rises as high as 4 feet in places) that is hot but not dangerous on its own. More dangerous are the razor sharp crystals beneath the surface, and the supersaturation of arsenic in the water itself.
Poisonous Water. Deliberately drinking the water in this tunnel triggers a Critical Failure.
Sharp Crystals. Beneath the surface of the water are the cloudy orange of quartz-orpiment, formed as the growing quartz sapped the arsenic and sulfur out of the water. Each time a creature moves 10 feet in this passageway it makes a Dexterity saving throw or takes 1d4 piercing damage.
Suspicious Color. Success on a Perception check identifies that the color of the water is off, suggesting that it is not clean and likely unsafe.
A group Wisdom check allows the party to protect themselves from exposure to the dangerously toxic water.
Critical Failure: Sharp, arsenic-laced crystals coalesce out of the cooling water, forming over skin and clothing. Each adventurer takes 35 (10d6) slashing damage, loses 2 (1d4) Supply , and is exposed to arsenic (page 165 in Trials & Treasures).
Failure: Arsenic-laced crystals coalesce out of the cooling water, forming over clothing. Each adventurer takes 14 (4d6) slashing damage, loses 1 Supply , and is exposed to arsenic.
Success: Using 1 Supply worth of materials per adventurer, the party protects their skin and equipment from direct exposure to the water.
Critical Success: Using materials salvaged from the caverns, the adventurers protect their skin and equipment from direct exposure to the water.