Located at the Southern foot of Mount Ryūgaishi, in Hamamatsu, Shizuoka Prefecture, is the Ryūgaishidō cave. It is one of the largest caves in the Tōkai region. It is about 1 kilometre deep, of which 400m is open to the public.
This limestone cave, like others around the world, was formed through the slow erosion of the limestone by rainwater, and it is estimated to be about 250 million years old. The cave was discovered by a university professor in 1978. As the route to go deep into the cave was very narrow, it was later mined by speleologists (scientists who study caves) and other cavers to make it more accessible for research and study. Some development work was done to the cave later to make it a tourist destination with restaurants and a museum.
Upon entering the cave, it feels pleasantly cool. It has an average annual temperature of a comfortable 18° Celsius, making it feel cool during the summer, and warm in the winter. Inside, limestone structures of stalactites and stalagmites have been formed through the slow dripping of water, forming impressive shapes and sculptures – works of art that is centuries old. These limestone structures grow approximately 1 centimetre per every hundred years! There is a sound of soft, piped music, and the sound of dripping water from the stalactites.
There are pools with crystal clear waters, tall stalactite chandeliers, as well as a natural underground waterfall that has a huge, 30m cascade. There is a stairway next to the waterfall for visitors to view the pool below. You can even feel the water as it splashes down, making you feel like an adventurer! The end of the trail is even left as it was mined – jagged and twisting, to give visitors a sense of how it was when the cavers dug the tunnels to access each area.
The route to tour the cave takes around 30 to 45 minutes. On the outside of the cave, there is also a museum that tells the history of how the cave was discovered and developed. Dioramas show the speleologists and other cavers digging and discovering the route of the Ryūgashidō cavern, and the tools that were used are also available on display. The restaurants and food stalls sell food that Hamamatsu is famous for, and visitors can try local specialties like grated yam, oysters, as well as ice cream made with the milk by the local Inasa cows.
