A portable ice bath is a folding or inflatable tub you fill, use and empty, costing a small fraction of a fixed plunge. For a lot of buyers it is the right first purchase, because it answers the only question that matters before you spend real money: will you still be doing this in three months?
What you are buying
Most portable tubs are a coated fabric barrel on a frame, or an inflatable ring tub, with a lid and a drain hose. Better ones add a layer of closed cell insulation, which is the specification that separates a tub holding cold overnight from one you re-ice every session. Read for insulation rather than for depth or color.
Where they beat a fixed plunge
They cost little, they need no plumbing, no circuit and no slab, and they store in a closet out of season. If you rent, if you are unsure, or if you want one at a race or a gym, portability is the entire point. Nothing about the cold water itself is worse in a fabric tub than in a cedar one.
Where they fall down
Without a chiller you are buying ice, and without insulation you are buying a lot of it. Fabric tubs need emptying and drying or they go musty, seams and zips are the failure point, and the ergonomics are poorer: you sit with knees up rather than reclining. Few survive years of daily use the way a rigid tub does.
Adding a chiller later
Many owners start with ice and add a chiller once the habit sticks. That works, but check the tub can take it: a chiller needs inlet and outlet ports or a hose kit, and an uninsulated fabric tub will run the compressor hard. If a chiller is likely, buying an insulated portable tub now saves replacing it.
Questions people ask about portable ice Bath
How long does a portable tub hold cold?
An insulated one can hold usable temperature overnight with a lid on. An uninsulated one warms within hours in summer.
Can you leave one outside all year?
Most makers say no. UV and freezing damage the fabric and seams, and a full tub that freezes solid can split the shell.
Is it worth adding a chiller?
Only once you are using it several times a week. Below that, ice is cheaper than the appliance and its running cost.