Kasplya (Russian: Каспля) is a river in Russia and Belarus, a left tributary of the Daugava River. Its length is 224 km, the first 157 km in Russia (Smolensk Oblast), and the rest in Belarus (Vitebsk Voblast). It starts from Lake Kasplya at (54°59′N31°38′E), and joins the Daugava in the town of Surazh.