E3M9: The Aquifer (Heretic)

From Doom Wiki

Heretic maps
City of the Damned
Hell's Maw
The Dome of D'Sparil E3M1: The Storehouse E3M2: The Cesspool E3M3: The Confluence E3M4: The Azure Fortress E3M5: The Ophidian Lair E3M6: The Halls of Fear E3M7: The Chasm E3M8: D'Sparil's Keep E3M9: The Aquifer
The Ossuary
The Stagnant Demesne
Fate's Path (deathmatch only levels)

This level occupies the map slot E3M9. For other maps which occupy this slot, see Category:E3M9.

E3M9: The Aquifer is the secret level in The Dome of D'Sparil episode of Heretic, and can be accessed from E3M4.