A Singaporean’s Guide to Using a Japanese Onsen [Updated 2021]

By Vivian Kek in Travel on 3 May, 2020

A Singaporean’s Guide to Using a Japanese Onsen [Updated 2021]

Is there an onsen in Singapore? I’m happy to report that the answer is yes!

Singapore may have its very own Sembawang Hot Spring Park, but you cannot call yourself a true-blue onsen lover if you haven’t been to the traditional ones in Japan. As for a conservative Singaporean like me, the idea of stripping off my clothes and bathing with a bunch of old Japanese ladies is honestly quite nerve-racking.

So to save you the awkwardness and prepare you for what you will find lurking among the steam, I’ve created the ultimate guide to the Onsen for Singaporeans. From the changing colours of the water to a tutorial on how to whip up a delicious onsen tamago straight from your home, here’s everything you need to know about the traditional practice.

What is an Onsen?

Infographic designed by Ikeda Spa

Onsen (温泉), is a Japanese hot spring that comes in many types, sizes, and shapes. As Japan is a volcanically active country, there are thousands of these pools located around the island.

Back in the 12th century, bathing in onsen pools started due to the influence of Buddhism. Buddhists believe that by immersing one’s body in ‘divine’ waters, the bather will be cleansed of the sins of the flesh, and the goodwill of the deities will be thus, conferred upon him or her.

It was only in the 17th century that people started recognizing the health benefits of the onsen, attracting travelers to the spring water.

Onsen Singapore - Rotenburo Outdoor Onsen at Ikeda Spa, Bukit Timah
Rotenburo Outdoor Onsen at Ikeda Spa, Bukit Timah

During the Winter Solstice, tangy fruits such as yuzu will be placed in the water to ward off colds in the coming winter! They also add a citrusy and refreshing fragrance to enhance the entire experience.

There is little to no doubt that onsens have always been an integral part of the Japanese’s lives. It has been ingrained in their culture to want only the best for their baths and taking a good bath to end off a busy day. They even relish going on onsen retreats to simply bathe, relax and bask in the feelings the calming water provides.

Onsen vs Sento: What’s The Difference?

Don’t get confused between the two! Though they are both considered to be public baths, the onsen and sento serve different functions. Think of the onsen as nature’s pool for relaxation and the sento as a man-made facility for the purpose of self-cleaning.

In kanji, sento (銭湯) translates into “coin” and “hot water” respectively. And if you can already deduce from its name, the sento is essentially a place where you can buy hot water to bathe or shower. Popular in the post-war era due to population increase and smaller houses to make up for it, many families turned to their local sento to bathe as not all houses came equipped with washing facilities. 

It’s been recorded that more than 20,000 sento existed in the mid 1960s, with only 5,000 left in Japan today. If you were to experience bathing in one of these traditional sento today, you’d have to venture into residential areas in order to do so. 

Before going to a sento, make sure to prepare soap, shampoo, towels, and toiletries should you need them later on. Once you’re there, make payment (about ¥460 for one adult in Tokyo) at the reception counter and proceed to the locker room to remove all your clothing. You may place your clothing into the lockers or lockboxes there.

After undressing, bring your small towel with you to the washing area. Before entering the shared bath, wash your entire body with hot water and soap so as to not contaminate the water. Once you’ve finished washing up in the sento, wipe your body dry and head to the locker room to redress, and you’re all done!

Onsen Etiquette: How to Behave?

Infographic designed by Ikeda Spa

When soaking in the pool, there are rules to follow before, after, and during the experience! Do keep these etiquettes in mind, otherwise, you might have to leave the onsen without even getting the chance to dip your toes in.

1. Wash With Cold Water

onsen singapore - wash hair before onsen

Before entering the onsen pool, washing your body squeaky clean is the foremost step to take. This is critical in preventing the water from being dirtied. Can you imagine how nasty the water would be if everyone just soaks in the onsen without washing up first? I wouldn’t even dare step foot in one!

It is also highly recommended to cool your body down with cool water before entering the warm onsen bath.

2. No Photography Allowed

onsen singapore - No photography

“Picture perfect memories”, I get that. But save your Instagram pictures for later as this is not the place anyone would want to get photobombed in.

An onsen is a place for everyone to relax and not be wary about who is going to snap a photo of them half-naked.

3. Stop Wringing Water Out From Your Wet Towel

onsen singapore - Towel on lady's head while she is taking an onsen

Accidentally dropped your towel into the water and attempting to dry it? Don’t wring it into the onsen bath!

I’m sure I don’t have to explain how wringing your perspiration into the water is unhygienic and disrespectful to the others soaking in the water after you. Instead, take it out of the onsen and wring it away from the bath. Alternatively, you can always ask for a new towel if needed.

4. Be Prepared To Not Wear Anything

onsen singapore - Naked lady in onsen

If you’re self-conscious about going in naked and wish to bring a swimsuit along, I’m sorry but you will not be allowed to enter the onsen. As one local Japanese person once told me, “You go in as you came into this world”. That means you’ll have to remove even your undergarments before entering!

Thankfully, at Ikeda Spa Singapore, we provide disposable undergarments for beginners to ensure that everyone’s comfortable!

😎 #FunFact 1: In Japan, there is a phrase – 裸の付き合い (Hadaka No Tsukiai) which translates to ‘naked friendship’. The Japanese will only reveal their body to the people whom they trust the most. Barriers are broken down once you are naked, and it is a good chance to relax and talk openly and honestly with one another.

5. Tie Your Hair Up

onsen singapore - rinse water

If you have long locks, make sure to tie your hair up as the onsen bath is only meant for soaking your body. For sanitary purposes, avoid having your hair touching the water.

6. No Tattoos Allowed

onsen singapore - Lady back with tattoos

In Japan, tattoos are deemed uncool as they have gang ties. Therefore, people with tattoos are prohibited from entering communal onsens. Yes, even those of you with tiny tattoos, unfortunately!

That’s not the end of the world though! People who have their bodies inked can still opt for a private soak at a typical onsen resort.

7. Avoid Soaking For Too Long

onsen singapore - Soaking in Onsen Bath POV

Being the kiasu Singaporean that I am, I would love to soak in the onsen pool for the longest possible time just to make my money’s worth. However, the longer you soak does not mean that you’ll get more nutrients absorbed into your body.

The recommended duration of soaking is not more than 15 to 20 minutes. It’s important to note that immersing yourself in hot water for too long will excessively raise your blood pressure or heart rate, causing dizziness and discomfort.

Therefore, the moment you feel uncomfortable, step out of the water and hydrate yourself immediately. Alternatively, soak for 15 minutes and leave for a cold bath before entering again.

😎 #FunFact 2: Notice people placing small towels above their heads? This is because the heat from the onsen will go through your body and all the way up to your head. The main purpose of the towel is to retain the heat from leaving your body and at the same time, cool down your head to prevent dizziness.

Onsen Benefits: Why Should You Soak In One?

Two words—relaxation and health benefits.

Infographic designed by Ikeda Spa

1. Reduces Stress

Warm baths generally aid in unwinding your body and mind after a stressful day. It helps that hinoki wood (the material commonly used to make traditional Japanese onsen tubs) also contributes to easing your mind of your worries.

Once in contact with hot water, this Japanese cypress wood releases hinoki wood oil that relieves anxiety and promotes a sense of balance. Its essential oil is widely used in aromatherapy as well to reduce the stress accumulated from school, work, or even life.

Ultimately, the synergy of hot water and hinoki wood is the perfect solution in melting the tension away.

😎 #FunFact 3: Other than reducing stress, did you know that hinoki wood oil also acts as a decongestant of the respiratory system that cures asthma and other nervous system ailments? Amazing, isn’t it?

2. Boosts Blood Circulation

Researchers from Japan found that people who suffered from chronic heart failure and soaked in hot springs actually experienced a decrease in blood pressure and an overall improvement of their symptoms.

As you sit in the water, your blood pressure drops, your blood circulation goes up and your metabolism kicks in a bit. I’m not going to lie, you’ll probably feel a little funny at first. But eventually, your body will automatically adjust to the temperature of the water and allow you to relax after that.

3. Nourishes Skin

Onsens that use hinoki wood are perfect for sensitive skin as it is gentle on the skin. In Japan, this Japanese cypress wood’s essential oil is traditionally used to treat skin irritations and injuries due to the antiseptic benefits that it has. 

Being highly therapeutic with essential oils in it, it gives restoration treatments. When bathing in the hinoki onsen, your skin will soak up all the goodness, making it feel soft and supple.

😎 #FunFact 4: Soap, antiseptics, perfume, cosmetics, and even hair treatments use the minerals and essential oils of Hinoki Wood! Now just imagine all of the benefits of going for an onsen!

4. Relieves Pain

As you have so cleverly deduced by now, onsens are generally pretty hot, typically measuring from 37-degrees Celsius to 42-degrees Celsius. This heat, although sometimes intense, can help relieve pain. The heat along with the pressure of the water dulls our perception of pain by blocking the pain receptors in our bodies. Interesting, right?

Moreover, the mineral concentration and hot water can make you feel “floatier”, which has positive effects on your joints and muscles as they work together to help you feel good and (more importantly!) more relaxed.

A review in Rheumatology revealed that spa therapy and balneotherapy (the “treatment of disease by bathing”) may also help to relieve lower back pain, especially at higher temperatures.

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Onsen Egg: How To Cook?

Onsen Tamago (温泉卵) directly translates to ‘hot spring eggs’ and are essentially eggs that are prepared in hot spring water to create silky egg whites and a custard-like yolk.

If you reside in Malaysia or Singapore and are familiar with half-boiled eggs, you’ll be happy to know that onsen eggs are similar but just ever so slightly firmer.

There’s no need to bring these eggs to an onsen to cook, all you need is one cooking pot and enthusiasm to make this delicious onsen tamago at the comfort of your own home!

Onsen Egg

What You’ll Need:

  • Cold Egg
  • Cooking Pot
  • Water
  • A bowl of Icy Cold Water

Step 1:

Fill your pot with water, boil till water starts to a rolling boil.

Step 2:

Remove pot from the heat. Wait for 1 minute and place cold eggs into the water without covering the pot with a lid. Do not try to move eggs.

Step 3:

After 12 minutes, remove the eggs carefully and put them back into ice-cold water. Make sure to cool the egg for 5 to 10 minutes until it has completely cooled all the way through.

Step 4:

Gently crack the egg open and the egg will roll right out. Do not crack open from a height, otherwise, the egg white will separate from the egg yolk.

Onsen Egg in Bowl

And voilà, you’re all done! Make sure to enjoy your onsen egg with some soya sauce! 😛

Onsen Milk: Why Drink After Bath?

There are various theories, but there is no exact reason. One of the most prominent explanations has to do with the war. After the war, when refrigerators were not widely used in ordinary households, public baths worked with milk producers because they used refrigerators to provide cold drinks.

It’s essential to drink water after taking a bath because you’ll be dehydrated. And you can now get fruit gyuunyuu (“fruit milk”) or coffee gyuunyuu (“coffee milk”) at most onsens nowadays!

Onsen Milk on Table at Onsen Bath

Onsen Water Colors: The Science Explained

Infographic designed by Ikeda Spa

If you’re under the assumption that all onsens are clear in colour, get ready to have your mind blown.

The colour changes depending on the elements and comes in a variety of colours, giving you different features and benefits when done soaking.

1. Milky White

Milky White Onsen

Milky white water is also known as Lou-sen water.

Sulfur is the element that turns the water into its aesthetically pleasing colour. When the fine particles of sulfur are unable to dissolve, they get exposed to the environment and oxidize with hot water. Although they are typically colourless and transparent, they turn clear water to a beautiful milky white hue when in contact with air.

Unsure if you are soaking in the Lou-sen water? If it smells like a rotten egg scent, you’ve got your answer.

The benefits of this onsen are impressive despite its unique foul smell. Here are some of its benefits:

  • Clears one’s throat
  • Enlarges blood vessels
  • Effective for heart diseases, arteriosclerosis, or other skin diseases
  • Helps with chronic bronchitis
  • Drug addiction treatment
  • Detoxification effects

Are you amazed yet? Just look at how beneficial it is to your body!

It’s also interesting to note that in Japan, many onsen places that claim to have great water have this Lou-sen water present. And yes, you guessed it—that makes it a very common type of onsen in Japan.

Travelling to Japan and want to try soaking in the Lou-sen water? Here are the places you can visit:

2. Brown / Red

Brown or Red Onsen

This reddish-brown onsen water is also known as Gantetsu-sen water.

The element that turns the water into this colour is iron. Similarly, iron is colourless and transparent like sulfur, but when oxidized, it turns the water chalky and changes its colour into a reddish-brown tint after.

One notable feature I’d like to bring to attention is its rust-smelling water. Although I won’t advise you to taste the water, you can still do so (if you’re adventurous) and find that it tastes bitter.

Soaking in the Gantetsu-sen hot spring allows your body to capture the iron and bring you these benefits:

  • Helps with anemia
  • Good for menopausal or menstruation disorder
  • Improves blood circulation

Having been known for bringing positive effects mainly for women, some call the water Fujin-no-yu, otherwise known as the Water of Women.

If you’re in Japan and wish to try this onsen, you can try:

  • Tatsuno-yu Onsen, Hyogo Prefecture

3. Black

Black Onsen

If you’re one for gothic culture, this Kuroyu (“Beautiful Skin Spring”), otherwise known as the black onsen, is the perfect place for you.

The cold mineral spring of humic acid turns the water black because of the size of its particles. Bigger sized particles turn the water black and opaque while smaller sized particles turn the water light-black and transparent.

With abundant minerals from the leaves and grass, this pretty hot spring brings these benefits:

  • Positive effects on skin
  • Warming to the core of the body

Seeking to improve your skin conditions in Japan? Then these are the places you should head to:

4. Green

Green Onsen

This green water is known as Moor Onsen due to the composition of organic vegetative substances.

The soothing and light green Moor Onsen contains fulvic acid, sodium hydrogen bicarbonate, and sulfur. However, the mechanism of the tone of the water is still unclear.

All in all, taking a dip in this pool can bring you these beauty benefits:

  • Rid toxins
  • Prevent cells from oxidizing (anti-ageing)
  • Tenderizing effect
  • Removal of dead skin cells

By removing your dead skill cells and providing you with anti-ageing skin properties, this “Hot Spring of Beauty” is sure to keep your skin protected and renewed!

To get these beauty benefits, the to-go place in Japan will be:

5. Blue

Blue Onsen

This blue water is actually a combination of milky blue and milky white water.

However, just like the green water, the mechanism of the blue water has not been clarified yet. Thus, it is only said that silicic acid and sulfur components are both related in turning the water blue in colour.

Known for these benefits, you can expect this from the water:

  • Strong moisturizing and soothing effect
  • Aiding neuralgia
  • Helps with muscle soreness and joint pains
  • Improves blood pressure
  • Eases fatigue

Looking for the perfect retreat to rejuvenate your body? Visit these places in Japan:

Onsen Scent: What Are The Different Aroma of Onsen? 

It’s no secret that onsen water has a distinct smell to it; the most notable being a sulfurous one as you approach a hot spring town. But did you know that onsen come in many different scents other than just sulfur? 

1. Sulfur

Most people describe this smell as the scent left lingering after the shooting of a gun or the end of fireworks. The scent is most prominent in onsen waters that contain hydrogen sulfide. Even a small amount of hydrogen sulfide is strong enough to produce such an overpowering smell. Fun fact? The milkier the water, the stronger the smell.

2. Rusting Iron

Now this may be the easiest one to spot. If your onsen water has a brown or orange tinge to it, or leaves a reddish tint on your tower after soaking, this water is high in iron and will smell rusty. Though it’s not as overpowering of a scent as sulfur, your nose will still pick up the slightly pungent smell of such an onsen. 

3. Tar

The mild smell of this onsen water may remind you of burning rubber, oil, or leather on a hot summer’s day. This is because the onsen water gets infused with sedimentary deposits before pooling into a large body of water to form a hot spring.

4. Minerals

If your onsen water smells appetising, chances are you’re in a hot spring that’s full of minerals. The subtle scent is something akin to kombu broth and can be found typically in mountain onsen. 

5. Iodine

Iodine concentrated water is strongly associated with the smell of mint or mouthwash. This unique water may also come in a deep red or orange tinge that can help you distinguish the difference between that and other onsen aromas.

6. Salt

Lastly, we have salt-infused onsen water. As you’ve probably already guessed, these waters smell like the sea and can often be found in onsen located by the seaside where a higher concentration of chloride can be found. 

At Ikeda Spa, we have our very own Hinoki Onsen Bath that not only gives you 5 different bath salt choices with an array of fragrances to choose from, but also releases mineral oils with soothing scents from the natural Hinoki wood for aromatherapy. 

Did You Know that Ikeda Spa is the FIRST Onsen in Singapore?

Onsen Singapore in Clarke Quay

Are you excited to visit one now? But have no trips planned to Japan? You can always come to Ikeda Spa for your regular dose of onsen goodness. And if you want a more private soaking session with your loved one, we provide private onsens and couple onsens.

Did I forget to mention that the onsen bath is free if you book any 90-minute treatment at Ikeda Spa? What are you waiting for? Click on the banner below to find out how!

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