As befits a proper megadungeon, Gloamhold is huge. It has many different levels and sub levels for brave adventurers to explore.
Megadungeons are a staple of many campaign worlds. Traditionally, they are the setting for a long campaign of exploration and delving. There’s absolutely nothing wrong with using a megadungeon in this way, but that’s not the only way they can be used.
A network of flooded, fractured caverns radiate outwards from beneath the Murkwater. The water therein is only fractionally above freezing and explorers need magic to survive for any length of time in this airless, lightless world.