MINAMI-SANRIKU, Miyagi >> A winery in Mi­yagi prefecture has adopted a unique method for aging its wine: storing it underwater.

The Minami-Sanriku Winery makes wine from grapes grown in the town and other areas and uses an oyster farming facility to keep its product at a constant temperature in the sea, where vibrations are transmitted through the water, resulting in a milder flavor.

“We want to make the wine a new specialty of Minami-Sanriku,” said a winery spokesperson.

In late April, wine bottles in oyster farming baskets covered in seaweed were pulled onto boats in Shizugawa Bay, Minami-Sanriku. The wine had been submerged for six months at a depth of about 32 feet, in a unique method called “under-the-sea aging.”

“The aging process is more than three times shorter than in a wine cellar, thanks to the vibrations caused by constant sound in the ocean, and the seawater temperature that doesn’t rise much even in summer,” said Michihiko Sasaki, winery president.

The winery is also run by Yuta Shoji, who is in charge of winemaking. The two took over the Minami-Sanriku Wine Project, launched in 2017 by the Local Vitalization Cooperator. The project was part of efforts to create new industries for reconstruction after the town was devastated by a tsunami following Japan’s cata- strophic 2011 earthquake.

The project led to the development of a vineyard on the slopes of the town, where daily temperature fluctuations are large and thus suitable for cultivating grapes. Operators crushed oyster shells, which are alkaline, and mixed them into the soil to aid in the grapes’ growth.

Shoji’s interest in wine as a hobby pushed him to become a winemaker. He quit his job at a book company in Tokyo in 2014, then worked at a grape farm in Ishikawa prefecture and a winery in Yamanashi prefecture, where he acquired his winemaking know-how. In 2017 he answered a recruitment call-out and became a member of the Local Vitalization Cooperator that same year.

After the earthquake, Sasaki left his job at a large company that produces musical instruments and moved to Sendai in 2014. Through his work selling wine glasses, he became interested in winemaking and joined the Local Vitalization Cooperator in January 2019. The following month, the two established the Minami-­Sanriku Winery.

Sasaki’s idea for under-the-sea wine-aging was inspired by wine found in sunken ships, and he and Shoji learned about the craft from another winery in the prefecture that had already been aging its wine underwater.

With the cooperation of local oyster fishermen, the partners submerged wine bottles in an oyster farm. The first 90 bottles of white, rose and red wine were placed in the ocean in February 2020 and pulled out in September. A second batch placed underwater in October was retrieved in April.

“The wine’s taste has softened and become more flavorful in such a short time,” Sasaki said.

Some winemakers think it takes about 10 years for the quality and yield of grapes to stabilize, and full-scale marketing has yet to begin. But slowly, they are achieving their dreams.

“We would like to eventually make wine a specialty of Minami-Sanriku that we can be proud of,” Sasaki said.