伏流也叫暗河，因岩溶作用在大面积石灰岩地区形成的溶洞和地下通道中，是具有河流主要特征的水流。主要在喀斯特发育中期形成，其发育及形态常受地质构造及裂隙的控制。通天河河道为敢沫岩内的伏流，河道两岸石笋林立，石幔成帘；石钟乳琳琅满目，千姿百态。 Subterranean river is also called the underground river occurring in karst caves and underground passages formed by karstification in the large limestone area. It is mainly formed in the middle stage of karst development, and its development and morphology are often controlled by geological structures and fissures. The Tongtian river watercourse is the subterranean river in the Ganmoyan. There are many stalagmites on both sides of the river. The stalactites spread everywhere in different shapes