Shimoda Onsen, which allowed us to enjoy their undisturbed straight-from-the-source natural hot springs, adheres to the rules of "do not boil, do not dilute, do not circulate." The more you learn about this location, the more interesting it becomes, not only for the quality of the water but also for the mysteries surrounding its origins. During our visit, we asked Maki Tanaka, a staff member at Shimoda Onsen's tourist information center, to tell us about the charms of the hot springs and how to enjoy it.

Shimoda Onsen is a hot spring that has been gushing forth for about 800 years in the Amakusa Shimoda districtof Amakusa City. It is also known as Shirasagi ("White Heron") Onsen because white herons used to heal their wounds there, making it a beloved hot spring resort in the area. If you visit Shimoda Onsen, the first place you should stop by is Platto - Shimoda Onsen Community Center located in the center of the hot spring town. Inside you can find a tourist information center where you can learn about the resort as well as general tourist information about the surrounding area.

We had the opportunity to interview Maki Tanaka from Platto - Shimoda Onsen Community Center. She is a member of such organizations as the Shimoda Onsen Ryokan Association and the Shimoda District Promotion Association, and is a inspiringly positive presence at Shimoda Onsen.

"Shimoda Onsen was registered as a national hot spring resort in 1963. As it was often used for therapeutic purposes, it is also a hot spring where you can certainly expect great benefits from using the hot spring," says Tanaka.

The waters of Shimoda Onsen rise from 250 meters underground, with a source temperature of 51.3℃, a weak alkaline pH of 7.84, and a sodium bicarbonate chloride spring. It is said that this water promotes skin turnover, promotes blood circulation, improves resilience to cold, and also moisturizes the skin similarly to a salt pack.

Even if you're not an onsen expert, you're sure to enjoy the chance to bathe in the all-natural hot springs, with no added or artificially heated water. Before she started working at the onsen, Tanaka had assumed that there wasn't much difference between hot spring water and bath water, but she recalls being surprised when she first bathed at Shimoda Onsen. "Since then, I've only been bathing in this hot spring. It's different in that you don't get cold as easily after bathing, cuts heal better, and your skin feels moisturized," she says.

"What's more, the origins of Shimoda Onsen are said to be a mystery, and have yet to be explained. Hot springs in volcanic regions are generally known to be heated by means such as magma, but Shimoda Onsen is said to be a non-volcanic hot spring, and apparently originates from the same layer as Amakusa pottery stone**. One theory is that it is heated by frictional heat from the stratum, but since it is not possible to see what is occuring underground, it remains a mystery to this day.

Furthermore, the hot spring is composed of a mixture of high-temperature water from deep strata and low-temperature groundwater and surface water from shallow strata. Normally, the temperature of hot spring water drops as it rises to the surface, but Shimoda Onsen, which gushes out 1,500 to 2,000 tonnes a day, is considered a hot spring area blessed with enough water to maintain a temperature of around 50 C," says Tanaka.

"Shimoda Onsen has three hot springs that bubble up along the Shimotsufukae River, which flows into the Amakusa-nada Sea. The hot springs are collected in one place and centrally managed, and shared with 13 hot spring inns, day-use bathing facilities, and a day care center. The hot spring area is small enough to be explored on foot, so you can enjoy touring the hot springs as you stroll around," says Tanaka.

We parked our car at Platto - Shimoda Onsen Community Center  and enjoyed exploring the hot springs. First, we crossed Yunomoto Bridge, which Tanaka recommended, saying, "I like the view of a hot spring town with inns lined up along the river," and headed to the first hot spring.

"There are no posted signs indicating the source of the springs, but when there is excess water from this hot spring, it is released into the river."
Just as Tanaka said, we took a look under the bridge, and...

We discovered a spot where hot water was coming out that seemed to be redirected from the source of the spring. The color of the surrounding area had changed, indicating that hot spring ingredients were adhering to the water.

As a hot spring enthusiast, I wanted to enjoy this spring, but at the time, the tide was high, and I couldn't reach it. Since it’s a river close to the sea, the water level changes with the tides, so I decided to visit again later.

Unfortunately, when we returned we found that the runoff water was not being discharged and we were once again unable to run our hands under the water. It seems that you can only do so when both low tide and an excess of spring water occur together. If you do happen to visit during such an occasion, consider yourself fortunate! Please be sure to visit and try your luck.

Continuing our walk, we arrived at Shimoda Onsen Shrine. Behind the shrine grounds is the source of the hot spring. We paid a visit to express our gratitude for the hot springs that have continued to flow for 800 years, and then headed to our next destination.

If you head towards the residential area on the opposite side of the river from the intersection where there are shops and "Igaya Ryokan", you'll discover a tank where the hot spring water is centrally managed from the source! The hot water that gushes out from the source is collected in this tank and then supplied to 14 facilities.

"In the past, each facility dug their own source, but there was a risk of the water drying up, so about 30 years ago, the association decided to manage it," says Tanaka.

The final destination on our tour of the hot springs is Shimoda Onsen Gosoku-no-Yu, a free foot bath.

The third hot spring source is located at the "Onsen Plaza," which has a foot bath.

The foot bath is available from 10:00 to 20:00, and because the hot spring water is poured in untreated from the source, the temperature near the outlet is quite high, so it may be quite hot. Relax and enjoy the water at your preferred temperature.

Currently, the inns are not accepting reservations for day trips to the baths. The only facility that offers day trips to the baths is "Shirasagikan."

E-bikes are available for rental until January 31, 2025, so you can enjoy cycling around the hot spring town and along the coast. Please contact Platto - Shimoda Onsen Community Center for more information.

                                  Spot information (as of December 20, 2024)