The observation deck tour is available from noon to 1 pm all year round.
It costs adult 1,000 yen, elementary school students 500 yen, 0~6 years kids Free.(1USD=108Yen)
The place where the deepest digging was done in this quarry, where rainwater is collected (water depth 30 to 40 meters).
The digging reaches a depth of 70 to 80 meters below the sea level in the Seto Inland Sea.