infrared, traditional, onsen or steam — a plain guide to sweating in bangkok

Bangkok has quietly become a good city to sweat on purpose in. There are onsen bathhouses, hotel steam rooms, traditional Finnish-style saunas, communal ice bath clubs, and private infrared suites - ours among them.

They get talked about as if they're interchangeable. They aren't. Here's what each one actually is, and - since we obviously have a preference - where the others are the better choice.

traditional sauna

What it is: a wood-lined room heated to 80-100°C by an electric or wood-fired stove, often with the option to throw water on hot stones for a burst of steam. Finnish in origin, social by design.

What it feels like: intense and immediate. The air itself is hot, so the heat arrives at your skin and stays there. Some people love that; some find it hard to breathe.

Best for: anyone who wants the classic thing. If you grew up with saunas or you want that specific full-blast sensation, nothing else replicates it.

infrared sauna

What it is: a cabin with panels emitting infrared wavelengths that warm your body directly rather than heating the air around you. Runs much cooler - ours sit at 75-80°C - while still producing a proper sweat. Full-spectrum units emit near, mid and far infrared.

What it feels like: like strong afternoon sun rather than an oven. The air stays dry and breathable. It takes a few minutes longer to get going, and then you sweat steadily rather than suddenly.

Best for: longer, more comfortable sessions; anyone who finds traditional saunas claustrophobic; people who want to actually relax rather than endure. It's also the easier entry point if you've never done heat therapy at all.

Worth knowing: infrared and traditional saunas are not the same treatment with different thermostats. The heat reaches you by a different mechanism, which is why the temperature numbers aren't comparable.

steam room

What it is: near-100% humidity at a much lower temperature, usually 40-50°C.

What it feels like: heavy, wet, enveloping. Excellent on the sinuses and on skin.

Best for: congestion, dry skin, and anyone who dislikes dry heat. Less useful if what you're after is a hard sweat or a cardiovascular effect - the low temperature limits how much of that you get.

onsen and bathhouse

What it is: the Japanese-style bathing tradition - a sequence of hot mineral pools, usually communal, usually with strict etiquette around washing beforehand.

What it feels like: slow, ritualistic, sociable. An afternoon rather than an hour.

Best for: the ritual itself, and for people who enjoy the communal side. If bathing with strangers is part of the appeal, this is the category to go to - and it's the thing a private suite explicitly isn't.

cold plunge and ice bath

What it is: immersion in cold water, typically somewhere between 5°C and 15°C. Ours run at 7°C, filtered continuously.

What it feels like: genuinely difficult for about fifteen seconds, then much more manageable, then quietly euphoric for an hour afterwards.

Best for: post-training recovery, mood, and the specific mental practice of choosing to do something uncomfortable and staying calm inside it. Best combined with heat rather than done alone - the contrast is where most of the interesting physiology lives.

so which should you choose

Honestly:

• You want the ritual and the company → an onsen or bathhouse.
• You want the hardest, most traditional heat → a Finnish-style sauna.
• Your sinuses are blocked → a steam room.
• You want recovery from training, or you want to sweat properly without an ordeal, or you want an hour where nobody can find you → a private infrared suite with a plunge. This is our category, and it's what we built.

The honest summary of the difference: most sweating in Bangkok is something you do near other people. What we do is the same physiology behind a door that's shut.

what a private suite means in practice

The word "private" gets used loosely, so to be specific - at sundaymood you get your own room containing the infrared sauna, the 7°C cold plunge, a hot rain shower and a changing area, for the full 60 or 90 minutes. Nobody else is in it. There's no communal changing room to cross in a towel, no waiting for the plunge, no adjusting your session around anyone else's.

You can bring one or two people if you'd rather not be alone - THB 400 each - and plenty of people book as a pair.

Sessions are THB 1,200 for 60 minutes and THB 1,800 for 90, with packages bringing that down substantially if it becomes a habit. We're on Sukhumvit Soi 24, inside the Sterling Sports & Wellness Centre.

questions people ask

curious rather than convinced? that's the right way round. book a single session and find out.