Fal'Zhardum Din

Fal'Zhardum Din is massive subterrenean cavern found underneath the calames jungle filled with geodes and glowing mushrooms.
The ceiling of the entire cave system glows with blue bioluminescent lights, and massive glowing vines that hang down, as well as some that "float" upwards. Grasping the true size of the cavern is made difficult due to the mushroom spores which that float throughout the air. Massive geode stones and geode veins also dot the ground, and the pools of water found within are an almost entirely opaque teal.

Description

A vast subterranean expanse, Fal'Zhardum Din is a cavern of immense proportions, its ceiling rising 150 feet above the uneven stone floor. However, what sets this cavern apart is its peculiar gravitational anomaly.
Found underneath the calames jungle and filled with geodes and glowing mushrooms, the cavern is one of the largest in the underdark.
The ceiling and floor of the entire cave system glows with blue bioluminescent lights emitted by mushrooms and massive vines. Vegetation from the ceiling appear to be upside down, hanging or floating strangely in the cavern. The abundance of mushrooms fill the cavern with spores which float throught the air. Massive geode stones and geode veins also dot the ground, and the pools of water found within are an almost entirely opaque teal.

Features

Gravity. At the midpoint in height, gravity reverses. Any creature or object crossing this threshold suddenly finds the ceiling becoming their new ground. As a result, the cavern is home to two mirrored ecosystems—one thriving on the cavern floor, the other clinging to the ceiling as though it were solid ground. Strange fungi, bioluminescent flora, and subterranean creatures have adapted to both orientations, creating a dizzying, otherworldly landscape where the sky is as alive as the earth.
Spores. The cavern is thick with drifting fungal spores. These spores form a dense haze that lingers in the air, reducing visibility beyond 60 feet and giving the cavern a dreamlike, almost otherworldly atmosphere.