| Category | Rivers |
| Continent | Brucrumus |
| Region | Onvorn |
| Map | Igreshand |
The Black Spiral is a wide Underdark river. It begins at Tara-Har and flows into the Ebonmurk. The river ranges in width of several hundred feet to one mile. The Black Spiral was the central lava tube for the volcano that once covered Tara-Har.