valley, ravine, gorge, chasm, cleavage (of breasts), part or place that has been left behind, blind spot, bottom (of society), (economic) trough, gap (in activity, one's work, etc.), lull, opening
渓谷【けいこく】
valley (with a river running through it), gorge, ravine, canyon
峡谷【きょうこく】
gorge, ravine, canyon, glen
谷底【たにぞこ】
valley floor, bottom of a gorge, bottom of a ravine
