Would you visit the oldest known hot spring in Japan?

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On this little excursion, we went into a little remote area in Wakayama along the Kumano Kodo to Yunomine Hot Spring to soak in the oldest known hot spring bath in Japan. I hope you can visit this hot spring, too!

Why should you visit a hot spring?

There are so many reasons! Here are a few:

  • The hot spring water relieves stiff muscles.
  • Hot spring baths help improve sleep.
  • The hot water improves circulation and oxygen flow, which helps the heart, brain, and overall health.
  • Minerals in the water treat skin issues.
  • Sweating leads to natural detoxification of the body.
  • It is relaxing and takes away stress.
  • The peaceful surroundings can bring tranquility to your mind.
  • It is an experience every traveler to Japan should have!

Where is "Tsuboyu," the oldest known hot spring in Japan?

Visitors from all around the world travel to the Kumano Kodo to take spiritual pilgrimages. This series of ancient pilgrimage trails, known as the Kumano Kodo, has a history of over a thousand years and is one of two world heritage pilgrimage sites (the other being Camino de Santiago).

Along the Kumano Kodo is one of the three main shrines, the Kumano Hongu Taisha Grand Shrine, that pilgrims visit. Travelers have options to stay in local area lodgings, such as Minshuku (small family-owned Japanese inns) and Shukubo (temple lodgings). 

Tsuboyu is in the heart of the Yunomine hot springs in the Hongu area right along the Kumano Kodo trail.

Yunomine Onsen area on Kumano Kodo map
Yunomine Onsen on Kumano Kodo map

What is special about Tsuboyu?

Tsuboyu is a small rock bath able to hold up to two people. Having been discovered over 1800 years ago, this mysterious hot spring is known for being the oldest hot spring in Japan. It was given a UNESCO World Heritage designation and is the only full-body hot spring bath with this designation in the world.

Tsuboyu was carved out of the natural stone and a boarded enclosure was built around it. The hot spring water in Tsuboyu changes color seven times each day. 

Tsuboyu and other hot springs in Yunomine are an essential stop for pilgrims along the Kumano Kodo route. Some of these waters have medicinal qualities and are considered helpful to healthy recovery for pilgrims struggling with illness. 

Yunomine hot spring resort
This is the place where we requested our reservation to soak in Tsuboyu. The cost was 800 yen per person. There were 2 reservations ahead of us.
Tsuboyu Onsen waiting area
This little booth above is where we were asked to wait for our turn to get in the Tsuboyu hot bath. The bath is down below in the shack-like building.
Once it was our turn, we went inside. Reservations to this Tsuboyu bath are limited to 30 minutes and 2 people at a time (solo is also okay).
The reason we chose to visit this hot spring is because it is known as the oldest hot spring in Japan, said to have been discovered around 1800 years ago. It also has been given a UNESCO World Heritage designation, the only one given to a full-body hot spring bath. An interesting aspect of this hot spring is that the water color changes about 7 times a day.

What can you do while waiting to get in the hot spring?

Anyone traveling along the Kumano Kodo will be impressed with the natural beauty around them. This stop is also beautiful with the tradional Japanese town setting, but that is not all. This is the perfect place to enjoy some boiled eggs cooked in the hot spring.

Near Tsuboyu is a hot well. Since the water is nearly 90 degrees celcius, it is perfect for boiling eggs or other vegetables sold nearby.

Yunomine hot spring eggs
Since we needed to wait our turn, we decided to boil some eggs in the hot spring. We bought 5 eggs for 300 yen.
Yunomine hot spring egg boiling well
The little fenced-in box area is where the well is for boiling eggs.
Yunomine hot spring egg bag
It was recommended to boil the eggs for 12 minutes in the hot spring. (No humans are allowed to soak in this egg boiling hot spring. 🤣 )
There were several nails and hooks available so I could hang the bag of eggs.
After 12 minutes or so, I pulled them out!
Yunomine hot spring egg yoke
Quite tasty with the rather firm yoke and somewhat runny white. The shop also provided a small packet of salt.

Was it worth the visit?

Yunomine Onsen bridge

Absolutely! Whether you are trekking your way along the Kumano Kodo and decide to stop when you cross this bridge, or if you simply choose to take a bus or car for a visit to the hot springs, you should fit this into your travel schedule. So, go ahead and add it to your bucket list!

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