Portable cold plunge · ~88 gallons
RIME One is an insulated, fold-flat plunge tub that sets up in about five minutes and folds flat when you're done. No plumbing. No electricity. No five-thousand-dollar install in a garage you might move out of.
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The RIME One
Insulated on all sides, sealed at every seam, and stable enough to climb into without a second person holding it. Fill it with a hose, add ice, put the lid on. That's the whole ritual.
Colorway — Obsidian
Leaves our US warehouse in 1–3 business days, then 3–7 in transit. Tracking on every order.
What ships to you
| Outside dimensions | 29.5 in dia × 29.5 in tall 75 × 75 cm |
|---|---|
| Capacity | ~88 gal / 330 L to the brim ~62 gal / 235 L at plunge fill |
| Fits | Adults up to 6′7″ / 201 cm |
| Shell | 5-layer: polyester/nylon outer, thick PVC, pearl cotton core, thick PVC, waterproof inner coating |
| Structure | 6 removable support rods + inflatable top collar |
| Water temperature range | 14–122 °F / −10–50 °C |
| Drain | Two bottom valves with hose fittings |
| Setup | About 5 minutes, no tools |
| Power / plumbing | None required |
| Warranty | 12 months against manufacturing defects |
Free shipping across the United States (lower 48). Orders leave our US warehouse within 1–3 business days and take 3–7 business days in transit. You get a tracking number as soon as it ships.
Plunge in it. If it isn't for you, tell us within 30 days of delivery and we'll take it back — you cover return shipping. If it arrives damaged or develops a manufacturing fault within 12 months, send photos and we'll replace it at our cost.
The evidence
We'd rather you buy this knowing what the research says — and what it doesn't. Every number below links to the paper it came from.
Measured in men immersed to the neck for one hour at 14 °C (57 °F).
Šrámek et al., Eur J Appl Physiol, 2000 · doi.org/10.1007/s004210050065
Same study, same hour in 14 °C water. Measured in blood, not in the brain.
Šrámek et al., Eur J Appl Physiol, 2000 · doi.org/10.1007/s004210050065
The dose that came out best for muscle soreness across randomised trials.
Machado et al., Sports Med, 2016 · doi.org/10.1007/s40279-015-0431-7
3,018 adults, 30 days of cold showers. Sick days fell; days actually ill did not.
Buijze et al., PLOS ONE, 2016 · doi.org/10.1371/journal.pone.0161749
And the honest caveats. A 2025 meta-analysis of 11 trials and 3,177 people found stress measurably lower 12 hours after cold-water immersion, along with better sleep quality and quality of life — but no significant change in mood, and a spike in inflammation immediately after. The hormone numbers above come from a full hour at 14 °C, not a three-minute plunge, and they were measured in blood plasma. If you lift for size, be aware that immersing straight after a resistance session may blunt muscle fibre growth (though not maximal strength) — plunge on rest days or a few hours later. Cain et al., PLOS ONE, 2025 · doi.org/10.1371/journal.pone.0317615 · Roberts et al., J Physiol, 2015 · doi.org/10.1113/JP270570
How it's built
01
Five bonded layers — polyester and nylon outside, thick PVC, a pearl cotton insulating core, more PVC, then a waterproof inner coating — plus a fitted cover for the top. Thin single-wall tubs bleed cold through the sides and the surface; this one is built to make a bag of ice last.
02
Six removable rods slot into sleeves around the body and an inflatable collar tensions the rim. The walls stay vertical when you climb in and out — no folding, no sloshing the water onto your feet, no second person holding the edge.
03
Two valves at the base take the included pipe and faucet, so sixty-odd gallons runs out to a drain, a slope or a flowerbed while you go and warm up. Tipping a full tub over is how most people end up with water in the garage.
04
Pull the rods, let the collar down, fold it. It goes under a bed, in a closet, in the back of a car. A permanent plunge is a renovation; this folds into a closet.
Setup
Lay it out, slide the six rods into their sleeves. No tools, no instructions needed after the first time.
~2 minutesTwenty pumps with the hand pump and the rim goes rigid. Drop in the seat cushion if you want one.
~1 minuteA garden hose fills it to plunge level. Cold tap water in winter is often most of the way there already.
~8–12 minutesAdd ice to hit your number, lid on while it settles, then get in and breathe slowly out.
~5 minutesIce calculator
The question everyone asks after their first fill. Move the sliders and we'll do the thermodynamics — how much ice it takes to pull your tap water down to your number.
The maths: energy to warm ice from freezing (334 kJ/kg to melt it, then 4.186 kJ/kg·K to bring the melt-water up) against the energy pulled out of your fill water, plus a 12% margin for heat leaking in from the air, the ground and the tub itself. Real life adds variables — a hot day, a long fill, a warm body — so treat it as a solid starting estimate, not a promise. A lid and reusable ice bricks both cut how much bagged ice you buy.
Honestly compared
We're not the coldest or the most permanent. We're the one you can set up tonight and put away on Sunday.
| RIME One | Bath + bags of ice | Stock tank | Plumbed plunge + chiller | |
|---|---|---|---|---|
| Typical cost | $119–$149 | $0 + ice | $150–$400 | $1,200–$15,000 |
| Insulated | Yes — walls, floor and lid | No | No, unless you build it | Yes |
| Full-body immersion | To the shoulders, seated | Legs out or shoulders out | Yes | Yes |
| Needs plumbing or power | Neither | Neither | Neither | Both |
| Packs away | Folds flat in minutes | — | It lives where you put it | Permanent |
| Drains without tipping | Two bottom valves + hose | It's a bath | Siphon or pump | Plumbed |
| Holds temperature unattended | Hours, with the lid on | Minutes | Minutes to an hour | Indefinitely |
| Takes over your bathroom | No | Every single time | No, but it takes your yard | Takes a room |
The protocol
Colder is not better. The research that found a benefit for muscle soreness clustered around 11–15 °C (52–59 °F) for 11–15 minutes — temperatures you can actually hit with a bag of ice.
Week one
The first thirty seconds are a gasp reflex, not an emergency. Get in slowly, keep your hands out of the water if it helps, and breathe out longer than you breathe in.
Weeks two to four
Add time before you add cold. When you can sit still and breathe normally for three minutes, drop the temperature a few degrees, not the other way round.
Ongoing
If recovery is the goal, the meta-analysis dose is 11–15 minutes at 11–15 °C. If it's the mental reset you're after, most people find two to four minutes does it.
Our promise
You can't judge a plunge tub from photographs, so we don't ask you to. Use it for 30 days. If it isn't for you, we'll take it back.
Used, wet and full of ice is fine. Tell us within 30 days of delivery and we'll arrange the return — you cover return shipping.
Seam leaks, valve failures and manufacturing faults are on us for a full year. Send photos, we send a replacement.
Email hello@rimecold.com and a human replies, usually inside one business day.
Owners
Questions
Can't find it? Email hello@rimecold.com and ask us directly.
As cold as the ice you put in it. There's no chiller — you fill it with tap water and add ice to hit your number. Our calculator above does the maths for your tub, your tap and your target. The insulation and lid are what make that ice last rather than melting out in an hour.
No. RIME One is built around ice, which is how most people plunge and by far the cheapest way to start. If you later decide you want set-and-forget temperature control every day, that's a different category of product — a plumbed tub with inlet and outlet ports and a compressor, starting north of a thousand dollars.
About once a week for one person, sooner if several people are using it or if it's outdoors in summer. Rinse off before you get in, keep the lid on between sessions, and the water stays clear far longer.
Anywhere flat that can take the weight and get wet: a garage, a patio, a garden, a basement with a drain.
Filled to plunge level it weighs roughly 580 lb (265 kg) before you get in — so think carefully about balconies and raised wooden decks, and choose a ground floor or a slab if you're not sure of the load rating.
About five minutes to assemble, then filling time. The rods slide into sleeves, the collar takes around twenty pumps, and after the first time you won't need the manual.
Yes — the outer layer is UV-resistant and winter is the easy season for cold water. Just don't let a full tub freeze solid; drain it if a hard freeze is coming, the same as you would a hose.
One at a time. It fits adults up to 6′7″ sitting with shoulders under water. Couples generally take turns and top up the ice between plunges — which is exactly what the reusable ice bricks are for.
Email us photos. Seam leaks, valve failures and manufacturing faults are covered for 12 months and we'll send a replacement — you won't be shipping a wet tub back across the country.
Free shipping across the United States (lower 48) right now, from our US warehouse. Orders leave in 1–3 business days and take 3–7 in transit.
For most healthy adults, used sensibly, yes — but it genuinely isn't for everyone. If you have heart disease, an irregular heartbeat, high blood pressure, Raynaud's, cold-induced asthma, diabetes affecting your feet or legs, or you're pregnant, ask a doctor before you start. Never plunge alone or after drinking. Read the full safety notes above.
Five minutes from folded
Free shipping, a 30-day guarantee, and a tub that packs away when you're done with it.