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Kaldera Plunge 80 vs Plunge 320: which tub should you buy?
·10 min read
Verdict: Buy the Plunge 80 at £69 if you want the cheapest real sit-in tub and you're happy to sort your own cover and hose. Buy the Plunge 320 at £109 if you'll plunge more than once a week: the insulated walls, the lid and the drain hose are the things you'd otherwise buy anyway, and the order clears the free-delivery line.
Feature
Kaldera Plunge 80
Kaldera Plunge 320
Price
£69
£109
Type
Round foldable sit-in tub
Round foldable sit-in tub
Dimensions (supplier figures)
80 × 75cm
83cm diameter × 73cm height
Capacity
Not published by the supplier
380+ litres (supplier figure)
Walls
Not specified by the supplier
Triple-layer insulated fabric
Lid
Not included
All-weather elasticated lid, included
In the box
Tub only, no lid or accessories
These are our two tubs, so this isn't a comparison where we pretend to be neutral about the brand. It's a comparison where we try to be honest about which of our own products you should buy, because selling you the wrong one is worse for us than selling you the cheaper one. The Plunge 80 is £69. The Plunge 320 is £109. Here is exactly what the £40 buys, what it doesn't, and who should pick which.
Plunge 80 or Plunge 320: the quick answer
If you plunge occasionally, mostly in the cooler months, and you don't mind rigging your own cover and draining with a garden hose, the Plunge 80 at £69 is the right tub and you'll be pleased with it. If you plunge more than once a week, or at all in summer, the Plunge 320 at £109 is the cheaper tub in the end, because the lid, the insulated walls and the drain hose are the things you'd otherwise be buying separately, and the order gets free delivery. Everything below is the detail behind that.
What's the same
Both are round, foldable, sit-in cold plunge tubs from the same category. You sit with your knees up and the water comes up around your shoulders. Both fold for storage and go through a standard door. Both work indoors or out. Both need a level surface, a tap within hose reach and somewhere to drain to. Both come from a supplier who doesn't accept change-of-mind returns, so on both you have your legal 14-day right to cancel after delivery with return postage at your cost, and anything faulty or damaged we replace or refund. Both are listed at 10 to 16 days for tracked delivery.
And in both, 12°C water is 12°C water. The cold is not what you're paying more for.
Size: nearly the same, not quite
The Plunge 80 is 80 × 75cm according to the supplier. The Plunge 320 is 83cm across and 73cm tall. So the 320 is 3cm wider and 2cm shorter. In practice you won't notice the difference sitting in them; both fit most adults with knees up. What you will notice is capacity: the supplier lists the 320 at more than 380 litres, and doesn't publish a figure for the 80. We won't guess one. Given the dimensions are so close, treat them as similar-sized tubs and plan for a few hundred kilograms of water in either.
This article is for general information and does not constitute medical advice. Cold water immersion is not a medical treatment. Consult a professional if you have cardiovascular conditions. Competitor prices and policies were checked at the date shown above and may have changed since.
Legal 14-day right to cancel, return postage at your cost; faulty or damaged replaced or refunded
Legal 14-day right to cancel, return postage at your cost; faulty or damaged replaced or refunded
One thing to be clear on: neither is a compact or travel tub. They're full sit-in tubs and you should check the footprint against your space before ordering either. Our will a Plunge 320 fit my space page walks through that; the answer for the 80 is almost identical.
Walls: the insulation question
The supplier specifies the Plunge 320's walls as triple-layer insulated fabric and says that helps the water hold its temperature for longer. The Plunge 80 is listed as a round foldable sit-in tub without a wall specification. We don't know what it isn't, so we don't claim it's uninsulated; we just can't tell you it is.
Why this matters: a tub of water is a big thermal mass, and once it's cold it wants to stay cold. The only question is how fast the air and the sun pull that cold back out. Insulated walls slow that, and a lid on top slows it more. In January in a UK garden, the difference is small; the tap water is cold and the air is colder. In July, it's the difference between topping up with a bag of ice and topping up with three. If you'll plunge in summer, the 320's walls are the bit you're paying for.
The lid
The Plunge 320 comes with an all-weather elasticated lid. The Plunge 80 doesn't come with one. The supplier's photo of the 80 shows a lid, but the listing doesn't confirm it, so we don't promise it, and you should assume there isn't one.
A lid does two jobs. It keeps leaves, insects and rain out of water you're leaving in the tub for days. And it keeps the sun off the surface, which is where most warming happens. It's a debris cover, not a filter or a water treatment system; our water care guide covers what you still need to do. Without it, you'll improvise with a tarp, or drain more often.
What's in the box
This is the biggest practical difference and it's worth reading slowly.
Plunge 80: the tub. That's the list. No lid, no pump, no drain hose, no cushion, no headrest ring, no manual beyond what's on the tub.
Plunge 320: the tub, the all-weather lid, six support legs, an inflatable seat cushion, a hand pump, a drain hose, a seal ring and the user manual. An inflatable ring forms the top edge and doubles as a headrest.
Three of those items change the daily experience. The lid, covered above. The drain hose, because emptying a few hundred litres by tipping is hard on seams and legs and emptying by hose is a matter of running it downhill and waiting. And the seat cushion, which brings a shorter person's shoulders up to the water and makes a ten-minute sit more comfortable for everyone. The headrest ring is a nicety; the hand pump is only needed because the ring exists.
Price and delivery: the real gap is less than £40
List prices are £69 and £109, so £40 apart. But orders under £100 carry a flat £4.95 delivery fee, shown at checkout, and orders over £100 ship free. So delivered, it's £73.95 against £109, a gap of about £35. Then price a lid, a drain hose and a cushion from a DIY shop and you're most of the way there before you've counted the insulation. We're not saying the 80 is bad value; we're saying that if you'd buy those bits anyway, it's not the cheaper tub.
If you'd use the 80 as-is, occasionally, with a tarp and a hose you already own, then it's genuinely £35 cheaper and that's real money.
With a chiller: which pairs with which
If you add a chiller later, the tubs point at different models, and this may decide it for you.
The Chill Core 300 at £599 is rated by its supplier for up to 300 litres and cools to about 15°C. That suits the Plunge 80 filled below 300 litres. It does not suit the Plunge 320, whose 380-plus litres exceed the 300's rating.
The Chill Core 500 at £799 is rated for up to 500 litres and cools to about 4 to 9°C. That covers the Plunge 320 with headroom, and would also run a Plunge 80 with ease.
The bundles follow the same logic. The Starter Bundle at £649 pairs the Plunge 80 with the Chill Core 300 and a Wireless Floating Thermometer; bought separately that's £697, so it saves £48. The Performance Bundle at £899 pairs the Plunge 320 with the Chill Core 500 and the thermometer; separately £937, saving £38. So the full chilled setup is £649 with the 80 and £899 with the 320, and the £250 gap is mostly the chiller, which buys colder water and more capacity. Our chillers guide has the full breakdown.
Day to day: what owning each one is like
Spec tables don't tell you what Tuesday morning looks like, so here's our honest picture of each.
Living with the Plunge 80. You fill it from the tap, add ice if you want it colder, and get in. Afterwards you either leave the water open to the sky or throw a tarp over it. When the water needs changing, you siphon it with a garden hose or bail it. There's nothing to pump up and nothing to lose. It's simple, and if you plunge a couple of times a week in the cooler months it's all you need. The friction shows up in summer: leaves in the water, warm surface by the afternoon, more ice than you expected.
Living with the Plunge 320. Setup takes a few minutes longer the first time: clip the six legs on, pump the top ring, drop the seat cushion in. After that the lid goes on and off between sessions and the water stays clear for longer. When it's time to change the water, you attach the drain hose, run it downhill and walk away. The headrest ring makes a ten-minute sit noticeably more comfortable. The friction is the ring wanting a few pumps now and then, and remembering to dry the tub properly before you fold it for the season.
Neither is hard work. The 320 is less work more often; the 80 is less to think about.
A note on what we don't know
We've been careful on this page to say "not published by the supplier" where that's the case, rather than fill the gap. The Plunge 80's capacity and wall construction aren't in the listing, and its water temperature rating isn't either, while the Plunge 320's are. That doesn't mean the 80 is worse on those points; it means we can't tell you, and we'd rather leave a blank than guess. If a detail matters to your decision and it's blank here, email us before you order and we'll ask the supplier.
Who should buy the Plunge 80
You're not sure you'll stick with cold plunging and want the cheapest real tub to find out. You plunge mostly from autumn to spring, when a UK tap is cold and insulation matters less. You already own a tarp and a length of hose. You want the simplest possible object with nothing to assemble beyond the tub itself. Or you're planning the Starter Bundle and want the 300-litre chiller pairing.
Who should buy the Plunge 320
You already know you'll plunge regularly. You'll plunge in summer. You want the lid in the box rather than improvised. You want to drain with a hose, not a bucket. You want a headrest and a cushion for a comfortable ten minutes. You want the tub to be ready for the Chill Core 500 later. Or you simply want it to work first time, out of one box, with free delivery.
Who should buy neither
If you want to lie flat, both are sit-in tubs and neither is for you. If you're very tall and broad, 80 to 83cm across is snug; sit on a kitchen chair with your knees up and measure before you order either. If you have no drain and no level hard standing, neither tub will be a happy purchase. And if you're in an upstairs flat, the floor loading of a few hundred litres of water is a question for the building before it's a question of which tub.
Returns, honestly
We'd rather say this twice than have you find out later. Our supplier doesn't accept change-of-mind returns on either tub, so we don't offer returns beyond your legal rights: you can cancel within 14 days of delivery under UK distance-selling law, with return postage at your cost. Faulty or damaged, we replace or refund. So measure, read the in-the-box list, and pick the right one first time. That's the whole reason this page exists.
Our verdict
For most people reading this, the Plunge 320 at £109. It's the complete tub, the walls are insulated, the lid and drain hose are in the box, and delivery is free. For the person testing the water on a budget, or building around the 300-litre chiller, the Plunge 80 at £69 is a proper tub at the lowest price we can sensibly sell one for. Whichever you pick, fill it from the cold tap, add a bag of ice, and give yourself ten minutes at around 12°C before you decide whether you need anything else at all.
This article is for general information and does not constitute medical advice. Cold water immersion carries cardiovascular and hypothermia risk. Consult a doctor before starting, never plunge alone, and stop immediately if you feel unwell.
