Kotumsar Cave

Check the season before you set out. The cave floods through the monsoon, typically mid-June to mid-October or early November, and the authorities close it while the water is high, so turn up in that window and you will see the gate and nothing else. Outside it you get a limestone tunnel of about 200 metres inside Kanger Valley National Park, with lateral and downward passages leading off the main line and pools that sit there permanently. It is the longest cave on the subcontinent, close to the bank of the Kanger river near Jagdalpur, in the forest tract old texts call Dandakaranya.