Nippara Limestone Cave

Located in the Okutama mountains at the western edge of Tokyo's administrative territory, Nippara is an 800-meter limestone cave system that formed over several million years. Inside, stalactites and stalagmites of various sizes fill chambers connected by narrow passages, and the largest chamber reaches a height of about 30 meters. The cave stays at a constant 11 degrees Celsius year-round, so bring a layer in summer. The site is within Chichibu-Tama-Kai National Park and accessible on the JR Ome Line, making it a realistic half-day trip from central Tokyo.