Canyon or ravine.
chasm, abyss
abyss
chasm
if you mean ravine, it is a deep narrow valley or gorge in the earth's surface worn by running water.
Gorge is a good word, could be a ravine.
A ravine is a deep, narrow gorge with steep sides, typically carved by running water. It is smaller than a canyon and often has a stream or river flowing at the bottom.
ravine
'une gorge' (fem.) is a French word; in French 'une gorge' is a narrow cleft with steep, rocky walls, especially one through which a stream runs (definition form dictionary.reference.com), or the throat.
Well, darling, that's what we call a gorge. It's like a fancy word for a deep crack in the earth with cliffs on both sides. So next time you find yourself in a tight spot between two towering walls, just remember you're in a gorge.
ravine, chasm, abyss, canyon, crevasse
gorge
A five-letter word for "narrow mountain stream" is "brook".