General Synonyms:
* Gully: A channel or ditch worn in the earth by running water.
* Hollow: A low area of land, often with a depression or dip.
* Cleft: A narrow opening or split in a surface, often vertical.
* Chasm: A deep, steep-sided opening in the earth.
* Canyon: A deep, narrow valley with steep sides, often formed by a river.
* Gorge: A narrow, deep valley, often with a river running through it.
* Ditch: A long, narrow trench dug in the ground, often for drainage.
More Poetic or Literary Synonyms:
* Défil é: (French) A narrow, winding pass or gorge.
* Crevice: A narrow crack or fissure, often in rock.
* Abyss: A bottomless pit or chasm.
The best synonym will depend on the specific context of your writing. Consider the size, shape, and formation of the ravine when choosing a word.