Contrast therapy means alternating between hot water immersion and cold exposure in the same session. At Zenva, that is built into both of our private rooms: a hot mineral-salt onsen paired with a separate ice bath, plus a Himalayan salt-wall sauna in the Bonsai room or a steam room in the Sakura room. Each room is private to your party for your whole booking.
What Is in Each Room
Both rooms include the same hot-and-cold pair. The onsen is kept at 40–41 °C. The ice bath is machine-chilled to 10–12 °C, so there is no ice to add or wait for. What differs is the heat room:
- Bonsai Room: hot mineral-salt onsen, ice bath, and a Himalayan salt-wall sauna.
- Sakura Room: hot mineral-salt onsen, ice bath, and a steam room.
A call bell in each room reaches our team at any point during your session. Both rooms take up to 3 guests, and the base booking is 60 minutes. Compare them on the Private Onsen Rooms & Packages page.
How a Session Works
There is no fixed protocol, so go at your own pace. This is a cautious first-time rhythm that matches commonly published guidance for hot soaks, sauna and cold-water immersion (see Sources below):
- Warm up in the onsen for 5–10 minutes.
- Cold: step into the ice bath for 30–60 seconds. A cold-shock response (fast breathing, a racing heartbeat) is normal; slow, steady breaths help it pass.
- Rest and rewarm in the onsen for another 5–10 minutes.
- Repeat two or three rounds. In the Bonsai or Sakura room, you can swap one hot soak for 10–15 minutes in the sauna or steam room.
- Cool down slowly, drink water, and finish on warm to relax or on cold to feel alert.
Experienced guests can lengthen the rounds, but longer is not better. Listen to your body and leave the water whenever you want to.
Safe-Use Guidelines
These points follow widely published advice on hot-spring bathing, sauna use and cold-water immersion. They are general information, not medical advice.
- Hydrate. Drink water before your session, between rounds and afterwards. People often underestimate how much they sweat.
- Skip alcohol, and avoid going in straight after a heavy meal or a hard workout (about 30 minutes of rest after exercise is a common rule of thumb).
- Build up gradually. Keep early ice-bath rounds short, and keep each sauna or steam round to around 10–15 minutes if you are new to it.
- Leave if you feel dizzy, faint, nauseous or unwell. Get out slowly with your head lowered, sit down, and press the call bell.
- Mind the wet floors. Walk slowly, use the mats and take care on steps when moving between the onsen, ice bath and sauna or steam room.
What Is Provided
Towels, robes and undergarments are provided. You are welcome to bring your own swimwear if you prefer. Please arrive 10–15 minutes before your booked time so you can settle in without rushing.
Commonly Reported Benefits
- Muscle recovery after exercise, travel, or long periods of standing or sitting.
- A mental reset: the temperature shift is often described as clarifying and energizing.
- Circulation: heat widens blood vessels, cold narrows them, and alternating the two is the basis of most contrast-therapy protocols.
We keep this section deliberately measured. Reviews of the research suggest alternating hot and cold water can help recovery after hard exercise, but some other reported effects, such as mood, are largely self-reported and people respond differently. Contrast therapy is a wellness practice, not a medical treatment. For a step-by-step first-timer's guide, see our Journal article on contrast therapy.
Our Recommended Way to Start: Onsen + Aromatherapy
If you want the full ritual, we most often recommend the private onsen followed by an aromatherapy massage. The heat leaves muscles warm and receptive to bodywork, and the session flows from one step to the next. Two current packages, each for 2 guests:
- Two, Together — 3,888 THB: 60 minutes of private onsen plus 60 minutes of aromatherapy massage (120 minutes in total).
- The Complete Zenva Reset — 4,588 THB: 60 minutes of private onsen plus 90 minutes of aromatherapy massage (150 minutes in total).
Prices are correct at the time of writing; please confirm when you book. More options are on the Onsen & Spa page, the Couples Spa page and the Massage & Spa Treatments menu.
What Guests Say
“The Mineral salt Japanese onsen and Ice bath are awesome. Highly recommend this place!”Google review, 5 stars
Frequently Asked Questions
How cold is the ice bath?
How hot is the onsen?
How long should I stay in the ice bath?
What is the difference between the Bonsai and Sakura rooms?
What is provided, and what should I bring?
Is contrast therapy safe for everyone?
What if I feel unwell during my session?
More answers about booking, cancellations and rooms are on our full FAQ page.
Sources
General guidance on temperatures, durations and precautions was drawn from: Oxford Brookes University: hot and cold, the health benefits of cold water immersion and saunas; Healthline: contrast baths; and Japan Spa Association: cautions for onsen bathing. Zenva's own water temperatures are as stated above.
This page is educational and general in nature and is not medical advice. If you have a pre-existing health condition, consult a physician before beginning any hot-cold contrast practice.
