| Category | Depressions |
| Continent | Brucrumus |
| Region | Cinazan, Miradelgûn |
| Map | Drenvun Depression |
Drenvun is a sunken land of eastern Brucrumus. Nearly 700 miles long, it starts at the base of the Damreth Peaks. Going south, it cuts through the red aura of Âruk, then east where it empties into Hullbreaker Bay.
Today, Drenvun is much different than its beginnings. In the making of Bal-Kriav, the northern part of Drenvun was a continuation of the Damreth Peaks, then Âruk's grasslands and wetlands. A Plaque of Alphar says that in the Creation War (1486 DE - 8777 DE) the land warped under the presence of so many dying primordials. Along a thousand mile battlefront, stretching from the bay to the mountains, the land was contaminated with entropic energy.
It was new tactic, a desperate one. In small amounts their entropic release is handled naturally, but flooding it with the energy of Chaos's dead brings about great unnatural change. Highlands turned to fields of rubble, expanses of perpetual sticky mud, aroma vents which will in time breed conflict, and worse, a sunken land, a division in what was openness.
In honor of the one who died scouting this area, I request that this area be known as Drenvun.
- Orallâchâr, captain in the 412th Covenant Recon - "Tale of Drenvun"
Since the Dawn Era, thousands of years later, the sunken land has turned into a wetland depression. There are pockets with dense foliage interlaced with bogs and rivulets. Some areas are tangled swamps impassable to most. There are thousands of ponds and murky pools.
The streams and rivulets coming down the Damreth highlands are the area's headwaters. Going south, these are joined by waterfalls and underground streams spilling out of cliff walls. During the Ice Cap Melt, Drevun sees much flooding.
In the area's more southern parts are floating settlements. Most rest on shambog islands. There are also many villages on stilts. These places are home to humanoids favoring the swampy conditions of the area, like the Graagvrii, trolls, and the Bullywug.
Drenvun's northern areas have tunnels diving into the subterranean reaches of Chaexidor. They link up with those leading to the kuo-toan empire of Âkhi. Raiders out of this empire traffic these tunnels frequently, debauching on the surface to snatch food, loot, and slaves.