What to Wear Under a Wetsuit (and How to Put One On)

The short answer: wear something thin, smooth, and quick-drying. For triathletes that means a tri suit. For training swims it means a swimsuit or jammers. For everyone it means no cotton, no board shorts, and nothing with a thick seam or a hard clasp.

The longer answer is worth two minutes of your time, because what you wear under a wetsuit changes how the suit fits, how fast you get out of it in transition, and whether you finish your race with a raw patch on your neck.

We fit wetsuits at the shop in Arvada year round, and this is the question we get most often from first-timers. Here is everything, including the part where you actually get the thing on.

What to wear under a wetsuit: every option

If you are racing a triathlon, wear your tri suit

This is the whole point of a tri suit. It is designed to be worn under the wetsuit for the swim, then to be the only thing you wear for the bike and the run. You strip the wetsuit in transition and you are already dressed.

The chamois in a tri suit is deliberately thin, unlike a cycling short, so it does not absorb pounds of reservoir water. It is cut close so it does not bunch under neoprene. It has a back zip or a front zip that lies flat.

Both men's tri suits and women's tri suits work the same way here. One piece suits are slightly faster in the water and slightly more annoying in a portable toilet. Two piece suits are the reverse. Neither choice is wrong.

If you do not own one yet, the rest of our triathlon apparel covers the two piece option, which is the more forgiving place to start.

If you are training, a swimsuit is fine

For practice swims at the reservoir, wear whatever you would wear in a pool. Men's swimwear in a jammer or brief cut, women's swimwear in a one piece. That is it. There is no performance reason to train in your race kit, and there is a good reason not to: the more you wear a tri suit, the faster the chamois breaks down.

What women should know

Two specifics come up constantly at fittings.

A sports bra under a wetsuit is fine, with conditions. Flat seams only. No underwire, no metal hooks, no plastic clasps. Anything hard sits between neoprene and your skin for an hour and creates a pressure point you will feel for days. Most tri suits have enough built-in support that a separate bra is unnecessary, which is the simpler answer.

A tankini or bikini top will move. Neoprene grips and pulls as you swim. If a top can shift, it will, and you will spend the swim thinking about it. A one piece or a tri top stays put.

What not to wear under a wetsuit, ever

• Cotton underwear or a cotton t-shirt. Cotton absorbs water, holds it, bunches into ridges, and chafes.
• Board shorts. Too much fabric, seams in exactly the wrong places, and they turn a tight wetsuit into an impossible one.
• Anything with a zipper, buckle, or clasp. Hard components press into skin under compression.
• Regular underwear. It is not designed to be wet. It bunches, it holds water, and it will chafe.

Are you supposed to wear anything under a wetsuit at all?

No rule requires it. USA Triathlon does not care what is under your wetsuit, and neither does any race director.

Plenty of experienced open water swimmers wear nothing. The suit fits marginally better without a layer between it and skin, and there is nothing to bunch. If you swim alone at a quiet reservoir and change at your car, it is a perfectly reasonable choice.

For most people the practical answer is different. You have to get from the parking lot to the water and back, usually past a few hundred other athletes, and a wetsuit that fails or a zipper that slips becomes a much bigger problem with nothing underneath. Wear something. It costs you almost nothing in speed.

How to put on a wetsuit without fighting it

Most people who say they hate wetsuits have only ever put one on badly. It should take ten unhurried minutes, and rushing is the single most common reason suits get torn.

Before you start

• Check your fingernails. Fingernails and rings do more damage to wetsuits than anything else. Trim your nails, take off rings and watches, and use the flats of your fingers rather than the tips.
• Give yourself ten minutes. Not two. If you are late to your race wave and rushing a wetsuit, you will tear a panel.
• Get a plastic bag. A grocery bag over each foot, and another over each hand, lets your limbs slide through the openings instead of catching. It looks ridiculous. It works better than anything else, and it is what we hand people in the fitting room.
• Lubricate first. Apply TRISLIDE or Body Glide to your ankles, calves, wrists, and neck before you start, not after the suit is on. Skip the crotch and armpits, which do not need it. The neck is the one place you should never skip, and we will come back to why.

The steps

1. Turn the suit inside out down to the knees. Roll the legs down so the inner lining faces out. You will roll them up over your legs rather than dragging the whole suit up your body.
2. One leg at a time, with a bag on your foot. Point your toes, slide your foot through, then work the neoprene up your calf in small gathers. Do not pull from the top.
3. Get the ankles right before you go higher. The suit should end at your ankle bone, not mid-calf. Every inch you leave at the ankle is an inch you will not have at the shoulders.
4. Work it up to the crotch and stop. Grip the fabric from the inside, in handfuls, and lift in small increments. The suit should sit high and snug in the crotch with no sag. This step decides whether the top half fits. If there is a gap here, everything above will be too tight.
5. Arms next, bags on your hands. Same technique. Small gathers, work each arm to the wrist, get the wrist seam sitting at the base of your hand.
6. Set the shoulders. This is the step people skip. Reach across, grip the neoprene at your armpits, and pull it down and in so the shoulder panels sit flat and low. Then swing both arms in a full circle. If you feel restriction across your back, the suit is not seated yet. Go back and lift more fabric up from your legs and torso.
7. Zip last, and get help. Hold the flap, have someone zip slowly and straight up. A zipper forced at an angle is a zipper that breaks.
8. Move before you swim. Windmill your arms, take a few deep breaths, crouch. Everything should feel snug and slightly restrictive on land. It will feel looser in the water.

How to take off a wetsuit fast

In transition, seconds matter and the same rules apply in reverse.

Start pulling the zip cord as you run out of the water. Get the suit off your shoulders and down to your waist before you reach your bike.

Step on the ankle cuff of one leg with the opposite foot and pull your leg straight out. Repeat. Do not sit down and tug at the cuffs with your hands.

Rinse it that day. Fresh water, inside and out, then hang it over a wide hanger or a shower rail. Never on a wire hanger, and never folded in a hot car.

How tight should a wetsuit be?

Tighter than feels reasonable, and looser than painful. A wetsuit works by trapping a thin film of water against your skin and letting your body heat it. A loose suit flushes cold water through constantly and does not work. A suit that is genuinely too small restricts your chest, and restricted breathing in open water is how a manageable swim becomes a panic.

How should a wetsuit fit? The checks that matter

Too tight or just new?

New neoprene feels alarming. Almost everyone's first reaction in the fitting room is that the suit is too small. Usually it is not.

On wetsuit sizing, go by the manufacturer's chart and not your clothing size. Orca, blueseventy, TYR, and SUMARPO all size primarily on height and weight, and their charts do not agree with each other. A medium in one brand is not a medium in the next. This is the single most common mistake in online wetsuit buying, and it is why we would rather you tried one on. Both men's wetsuits and women's wetsuits are in stock in full sleeve and sleeveless cuts.

The neck rash nobody warns you about

Wetsuit chafing on the neck is the most common injury in beginner triathlon, and it is entirely preventable.

Here is what happens. You rotate your head to breathe roughly every three strokes. Over a 750 meter swim that is several hundred rotations, each one dragging your jaw and the underside of your chin across the neoprene collar. Salt or silt in the water turns that collar into fine sandpaper. You do not feel it during the swim because you are cold and busy. You feel the wetsuit rash in the shower that night.

The fix takes ten seconds. Wetsuit lube is the one accessory nobody thinks to buy and everybody wishes they had. Apply it generously around your entire neck and the top of your collarbones before you put the suit on. TRISLIDE sprays on and is easier to apply thickly. Body Glide is a stick and travels better in a transition bag. Either works. Not doing it is the only wrong answer.

Reapply on race morning even if you lubed up at home. And if you are prone to it, run a thin line under the arms where the suit meets your armpit as well.

Wetsuits, water temperature, and Colorado

Colorado adds two wrinkles: reservoir water stays cold well into the season, and our racing window is short.

What USA Triathlon actually allows

Individual race directors set their own cold-water floor, commonly around 58 to 61°F, below which a wetsuit becomes mandatory rather than optional. Check your race's athlete guide, because that number is theirs and not USAT's.

What this means here

Front Range reservoir water runs roughly in the high 50s in May, high 60s in June, and mid to high 70s in July and August, cooling back into the low 70s by September. Actual race-morning readings vary by reservoir, depth, and the week, and race directors post the official temperature on race day.

Practically speaking: nearly every Colorado triathlon you will enter is wetsuit legal, and most of the early season races are cold enough that you will genuinely want one. A May or early June race in water in the high 50s is not a suit-optional situation for a first-timer. That is the water where a wetsuit stops being about speed and starts being about not having your breath knocked out of you in the first fifty meters.

The exception is the occasional late July or August afternoon race where water pushes past 78°F. That is where a swimskin comes in. It is a non-insulating suit that is legal above the wetsuit cutoff and offers some of the hydrodynamic benefit without the neoprene. It is a second purchase, not a first one.

Practice in the suit before you race in it

Do not let race morning be the first time you swim in your wetsuit. The compression across your chest changes how your breathing feels, and the added buoyancy changes your body position and stroke. Two or three open water sessions in the suit is enough to make it feel normal.

If you are not sure you want to own one yet, rent a wetsuit for five days and take it to the reservoir. Rentals start at $60 and come in both full sleeve and sleeveless. It is the honest answer for anyone racing once this season to find out whether they like the sport before spending several hundred dollars.

Getting it right the first time

Wetsuit fit is one of the few things in triathlon where twenty minutes in a shop genuinely beats hours of research. Sizing charts disagree between brands, torso length matters more than most people expect, and the difference between a suit that fits and one that nearly fits is obvious the moment you have both on.

Come by the shop at 14715 W 64th Ave in Arvada and try a few. We will get you into the right size, show you the plastic bag trick in person, and send you out with lubricant so your first open water swim does not end in a neck rash.

While you are planning, our sprint triathlon distances guide covers what you are actually training for, and the 2026 Colorado triathlon race calendar and 2027 Colorado triathlon race calendar will help you pick the race. You will want goggles that seal, too, but that is another article.

Frequently asked questions

Do you wear anything under a wetsuit?

You do not have to. No rule requires it. Most triathletes wear a tri suit because they race in it afterward, and most swimmers wear a swimsuit for practicality. Some experienced open water swimmers wear nothing at all, which is legal and slightly faster.

Do you wear a bathing suit under a wetsuit?

Yes, that is the most common choice for training swims. Any swimsuit works as long as it is thin, smooth, and free of buckles or hard clasps. For racing, wear a tri suit instead so you do not have to change in transition.

How tight should a wetsuit be?

Snug everywhere, with no loose folds or gaps at the neck, crotch, or lower back, but never so tight that you cannot take a full deep breath or rotate your shoulders freely. It will feel tighter on land than in the water.

How do you put on a wetsuit more easily?

Give yourself ten minutes, trim your fingernails, put plastic bags over your feet and hands, and work the suit up in small gathers rather than pulling from the top. Get the crotch seated properly before you start on the arms.

Will a wetsuit chafe my neck?

It will if you do not lubricate. Apply an anti-chafe product like TRISLIDE or Body Glide around your neck and collarbones before putting the suit on. This is the single most common beginner mistake, and it takes ten seconds to prevent.

Do I need to buy a wetsuit for my first triathlon?

Not necessarily. Renting is a sensible first step if you are doing one race to see whether you like the sport. If you plan to race more than twice a season, buying usually makes more sense within the first year.