The Below

Overview

A vast collection of lakes and caverns stretching far into the planet. This is due to the planet being made of a mix of softer and harder stones. The softer stone has mostly worn away to form large caverns, which remain supported by the harder stone. Because of this, many resources are exposed in caves. The Below is believed to have been created by the Architect.
The Below’s water cycle is the result of water flowing to the depths of the planet then vaporizing and making its way back up. Surface seasons affect this water cycle. As rainfall increases, so too does the humidity of the below, which in turn causes fungi to release spores, which is used to mark years.
Beneath the oceans lie deserts, with little to no water. A surprising number of caverns are unflooded, thanks to the strong stone beneath the ocean floor.
Much of the below is filled with chemosynthetic plants and fungi, as well as a wide collection of creatures who make up the Below's vast ecosystem. These vary by biome.
The Below is rife with gemstones and minerals, as well as thaumic geodes. Thaumic geodes are essential for many biomes of the below.

Biomes

Plain: A typical cave area, home to chemotrophic fungi and animals which subsist off of them.
Desert: Regions below the oceans, with little to no water. A surprising number of caverns are unflooded, thanks to the strong stone beneath the ocean floor, and so deserts are the most common biome in the Below. However, they are rarely traveled.
Lake: Lakes are bodies of water home to aquatic creatures and plants. The high levels of moisture within these caves allow for vast swathes of lichen to grow throughout them.

• Seasonal Lake: A lake which disappears during the dry season, or only appears during the wet season.
• Oasis: A small lake within a large plain or desert.

River: Flowing water, usually connecting to one or more lakes. Various plants and animals both aquatic and terrestrial call rivers their home.

• Seasonal River: A river which disappears during the dry season, or only appears during the wet season.
• Delta: A spot where a river splits into several streams through silt deposits where it meets a lake or other river.

Sinkhole: A large hole to the surface where stone has worn away.

• Sunken Forest: A sinkhole with a lush forest at its bottom, rather similar to those above on the surface.
• Sunken Lake: A sinkhole with a lake at the bottom, ripe with photosynthetic plants.
• Pit: A sinkhole that does not connect to the surface, rather a much deeper portion of a cave. Species here may be different from those above.

Mushroom Field: An area with large quantities of mushrooms and other fungi, which have degraded stone into soil.

• Fungal Marsh: A mushroom field with enough moisture to become a wetland.

Radiant: Any form of biome centered around one or more light geodes or reservoirs, home to a wide variety of plants.

• Radiant Forest: A radiant biome with large trees or other plants, likely with a geode towards the top. Geodes in other places will result in crowding of plants, which are also less likely to be tall.
• Radiant River: A radiant biome intersecting a river.
• Radiant Lake: A radiant biome below water.
• Radiant Marsh: A radiant biome within a fungal marsh, the fungi here are massive, and compete with other plants.

Thermal: Any form of biome centered around one or more flame geodes or reservoirs for heat, or located deep enough to be warmed by the planet’s heat.

• Thermal Forest: A thermal biome with large trees or other plants.
• Thermal River: A thermal biome intersecting a river.
• Thermal Lake: A thermal biome below water, its surface is rather pleasant.
• Thermal Marsh: A thermal biome within a fungal marsh, the fungi and plants here thrive.

Frigid: Any form of biome centered around one or more frost geodes or reservoirs, or located high enough within a mountainous or cold region to be chilled.

• Frigid River: A frigid biome intersecting a river, its surface may freeze.
• Frigid Lake: A frigid biome below water, its surface may be frozen.

Verdant: Any form of biome centered around one or more growth geodes or reservoirs, home to massive fungi and other chemotrophic plants. Additionally, some rare thaumitrophic plants grow here.

• Verdant Forest: A strange verdant biome with large fungi and thaumitrophic plants.
• Verdant River: A verdant biome intersecting a river.
• Verdant Lake: A verdant biome below water, it is filled with large aquatic plants and animals.
• Verdant Marsh: A verdant biome within a fungal marsh, the fungi here are massive.

Maps

• 

  The Below

Type

Underground / Subterranean

Inhabiting Species

• Deep Lichen
• Deepslimes