The damp and dark environment almost forever lacks bright and steady light sources, enveloped everywhere by a cold, melancholy atmosphere. The water here is utterly toxic to mortals.
Excessive acidity is secondary; the main issue is that the water here isn't dihydrogen monoxide at all... but some kind of hydrogen-helium compound, half as light as regular water, utterly unusable for consumption by living organisms.
Alright, since the so-called 'water' is this abstract, the environment and physical laws here are even more outrageous.
The thermometer Long Yuqiong carried exploded directly — the lowest temperature at Layer Abyss, absolute zero, is minus 275°C.
As for Border Abyss's absolute zero...
Border Abyss does not have an absolute zero.
This abstract hydrogen-helium compound of Border Abyss is utterly unable to serve as a reference standard, so they can only use the water brought over from Layer Abyss as a reference.
