A Tokyo firm is hoping that the aging of wine at an undersea cellar off Amami-Oshima Island in Kagoshima Prefecture will help revive the local economy.

Underwater aging of wine is a widely held practice around the world, as submerged conditions — consistent and relatively cool temperatures, higher pressure and the absence of excessive light — are suitable for wine to gracefully mature.

But the process is "rarely practiced in Japan," said Yui Moritani, the 38-year-old president of a public relations firm in Tokyo that began the project.

In late January, about 500 bottles of European wine in stainless steel cages were lowered to the seafloor at a depth of about 20 meters off the town of Setouchi in the southern part of the island.

The firm opened a restaurant serving wine in the town in November.

Bottles of wine are submerged in the Oshima Strait off Setouchi for maturation on Jan. 30.
Bottles of wine are submerged in the Oshima Strait off Setouchi for maturation on Jan. 30. | Kyodo

Most of the bottles submerged in January will be left in the sea until June to be served for customers in July. Some of them will be aged longer to figure out the right maturation period for optimal taste.

The company also plans to provide an underwater aging service for wine bottles entrusted by customers in the future.

Moritani also hopes the project will improve the environment, with the underwater wine cellar serving as an artificial reef to attract fish and a seaweed bed, which will absorb carbon dioxide.

A diver who helped sink the wine bottles said that water in the area is warmer than typical temperatures for aging wine, measuring 21 degrees Celsius on Jan. 30, but that there is a merit in that wine can age rapidly in such conditions.

"The most significant challenge is whether wine can make it through summer in the warm water," Moritani said.