Aogashima is a small islands with a population of only 160. It is known for its double caldera volcano. Such a structure only exists in a few places in the world. Inside of the volcano, you can feel the geothermal heat and it is a renown place for stargazing.
From the heat of the volcano, an incredible condiment is made: Hingya Salt. Hingya, in local dialect, means fumarole. Sea water is heated with the geothermal heat. It takes around 13 days for the salt to crystallize. After crystallization, the excess water is removed and the salt is set to dry using only, once again, geothermal heat. Hingya salt is known for its high amount of calcium and magnesium.