On the Ratnapura to Ambilipitiya road between Godakawela and Pallebedda junctions, there’s a road to the right side which leads to Kumburugamuwa. From the main road, you need to travel about 13km on a mountainous narrow road to reach Waulpane village. Unfortunately, I wasn’t tracking the road on GPS, but remembered to mark the location.
The cave is owned by bats (100s of them) and is very very dark. Cave ground has at least an inch thick bat droppings, may be a bit less on the path where people usually walk