Anvil Vale Underwild

The layer directly beneath the surface is referred to by dwarven geologists as the "underwild," a liminal space where the horrors of the deeps may sometimes rise to, and creatures from the surface may seek shelter within, giving rise to a uniquely dangerous strata that forms the topmost layer of the underdark. In the Vale, the underwild is made up of the Patrolled Undervale and the Near-Wilds, with the Underice Sea a notable geological feature in the northern reaches of the underwild.

The Patrolled Undervale

Troops of soldiers set out every four hours from the Gates to undertake twelve-hour patrol shifts into this part of the underwild, making short work of dangerous beasts that wander into the area and making sure that nothing sets up any kind of lair within those spaces.

• By and large the animals of the underdark are left alone, although any that get large or numerous enough to endanger folk are often dealt with.
• In many ways, this is a natural wilderness like Thanewood: patrolled so as to avoid allowing it to become home to dangerous monsters, but not exactly civilized. Those who venture into it do so at their own risk.
• Most of the passages from this layer into the Deeping Dark below have been sealed off, but occasionally something from below breaks through.

The Mithril River

• Glacial run-off that does not end up in the Underice Sea is usually drawn into a single, low-lying course, which forms the Mithril River, a subterranean river. This river runs from various Near-Wilds sources but becomes a proper river in the Undervale, flowing south away from its source.
  • Many miles away, the Mithril River once against surfaces, pouring out of a cliffside and forming the Silver River, which winds away to the Five Rivers Basin.

The Underloch

• The Mitril River is joined by the waters of Loch Winter that pour underground and into the river at the southern end of the Vale to form the Underloch.
• The House of Ergenn: Where one of the dwarf-wrought passages of the Undervale ends on the shores of the Underloch, there sits the House of Ergenn, a fortified sanctuary that offers a life of quiet contemplation. The ascetics of Ergenn's House are private and largely insular, although the abbot of the House does occasionally seek the company of the high and mighty to ask of them support for the House.

The Near-Wilds

Unlike the Patrolled Undervale, the Near-Wilds are unpatrolled and home to quite dangerous creatures.

• Though the dwarven military patrols and Black Shield will engage and eliminate any settlements of dangerous creatures or lairs of large predators once they become aware of them, it is entirely common for very dangerous things to make the Near-Dark their home and hunting ground.

The Underice Sea

Sitting in the highest reaches of the Starfrost Mountains is the Eternal Ice, a great glacier that spans miles of mountainous terrain above the freezing line. The years and weight of the ice itself have packed down the glacier's substance until it is an almost eerie glowing blue ice, particularly by the light of the moon.

• This glacier's lowest levels melt constantly into a thousand fresh water rivulets that form the various lochs of the Starfrost Mountains, but that also find their way into a vast cavern north of the Vale.
• This cavern is home to a great underground sea. Its black expanses are so deep that it effectively reaches down into its own sub-aquatic deepingdark pocket.