A wetsuit's sleek, second-skin appearance might seem straightforward, but what do you wear under it?

Since their invention in the 1950s, wetsuits have revolutionized how we enjoy and experience water activities in varying temperatures.

What you wear under your wetsuit affects how comfortable — or not — you feel and how much and how well you enjoy your underwater explorations. The right choice means you feel comfortable and can spend time scuba diving. The wrong choice means you get out of the water quickly feeling miserable, uncomfortable, and cold.

So, let’s see what you could choose to wear under your wetsuit to maximize how much you enjoy your scuba diving.

Common Undergarment Options

For Everyone

Rash Guards/Compression Shirts

These form-fitting, quick-drying garments protect your skin from the neoprene and prevent the notorious "wetsuit rash" that can occur from repetitive movement against the suit's seams and material.

They also add a thin but effective thermal layer that helps trap more body heat. Rash guards are available in various thicknesses and sleeve lengths and are particularly helpful for shoulder-intensive activities like paddling and surfing.

They are made of synthetic fabrics (Lycra, polyester blends) to reduce drag in the water and wick moisture away from the body. They also offer UV protection.

Nothing (Going "Commando")

A surprising number of water sports veterans prefer wearing nothing under their wetsuits. The wearing nothing approach maximizes the direct contact between neoprene and skin, which technically improves the wetsuit's heating efficiency as it minimizes layers that can trap water and cause cooling. By going commando, you don’t have to worry about the fabric bunching, riding up, or shifting when you are the most active underwater.

However, if you like the going commando option, thoroughly rinse your wetsuit after each use for maximum hygiene and to prevent bacterial growth. It's generally not recommended if you are renting a wetsuit for obvious sanitary reasons.

Wetsuit Liners

A wetsuit liner is a very thin, full-body extra layer that looks like lightweight long underwear but has technical features designed for water immersion. These liners include thermal technologies like infrared reflection, water-repellent coatings, or brushed interiors that maximize warmth without adding bulk. They distribute pressure evenly across the body to reduce discomfort points during long diving sessions. While more expensive than other options, dedicated users find them worth the investment, especially in colder water conditions where temperature regulation is paramount.

Neoprene Shorts/Tops

These additional neoprene pieces, worn underneath your wetsuit, provide targeted insulation for core body areas. Made from the same material as the wetsuit, they integrate seamlessly with your primary wetsuit and add millimeters of insulation where it matters most.

Core body warmth prevents hypothermia and helps you enjoy your underwater exploration. These pieces are handy for activities in variable temperatures, as they can be added or removed depending on conditions. You can make your wetsuit system more adaptable to changing environments or seasons.

For Women

One-piece Swimsuits

Athletic-style one-piece suits offer comprehensive coverage with minimal seams and potential pressure points.

The continuous fabric distribution helps prevent the uncomfortable bunching or gathering that can occur with two-piece options. Modern performance swimwear incorporates compression technology, flatlock seams, and strategic panel construction, complementing rather than competing with wetsuit design.

Look for racerback or competitive styles rather than fashion-oriented designs with decorative elements that could create pressure points under the wetsuit’s tight neoprene.

Sports Bikinis

Unlike decorative beachwear bikinis, sports-oriented two-piece swimwear is specially designed for outdoor activities.

Sports bikinis are designed to stay firmly in place during activity and movement. Features like wider straps, cross-back designs, underwire-free construction, and higher necklines make these ideal for active water sports.

The fact that there is a top and a bottom can offer advantages for thermoregulation in different water temperatures. 

Wearing a bikini can make your bathroom break more comfortable. Because it can be challenging to wear a one-piece suit under a wetsuit, many women prefer sports bikinis, especially for long sessions.

Swim/Board Shorts with Sports Bras

This combination offers the support of technical sports bras and the coverage and anti-chafing benefits of swim shorts.

The sports bra component features moisture-wicking fabrics, minimal hardware, and compression without constriction for optimal comfort under pressure.

Board shorts designed for active use (rather than fashion styles) feature four-way stretch material, minimal seams, and quick-dry properties.

This pairing is perfect if you experience chafing in the inner thigh area or prefer additional coverage and support in and out of the water.

Sports Underwear Sets

Athletic-focused underwear differs from everyday undergarments in both design and materials.

Technical sports underwear sets use synthetics that control moisture, temperature, and movement.  

Unlike cotton underwear, which becomes heavy and abrasive when wet, proper sports underwear remains lightweight and reduces friction even after hours of immersion. These sets feature wider waistbands, seamless construction, and anatomical designs that prevent riding up or shifting during vigorous movement.

Rash Guard/Surf Shorts Combination

This popular pairing works against the two most common wetsuit discomforts: upper body chafing and inner thigh irritation.

The rash guard component extends protection to the torso, shoulders, and arms—areas prone to abrasion during paddling movements.

Meanwhile, the surf shorts protect the sensitive inner thigh region where repetitive leg movements can cause painful skin irritation.

Women can customize this combination of coverage and thickness to adapt to different water temperatures and activity intensity (sleeve lengths and material weights).

For Men

Swim Briefs/Jammers

Competitive swimming-style jammers extend from the waist to just above the knee and offer additional thigh protection without excess fabric that could bunch uncomfortably.

The streamlined profile of briefs or jammers integrates almost seamlessly under neoprene to limit water entry and movement resistance.

The snug elastic waistbands and leg openings are designed to stay in position no matter how hard you swim or move underwater.

Board Shorts/Trunks

Board shorts or trunks are a common choice for many male water enthusiasts, particularly if you like to combine casual beach activities with underwater exploration.

While convenient, standard board shorts come with drawbacks when used under wetsuits.

Excess fabric may gather along the legs and waistline, creating uncomfortable pressure points and potential water channels, decreasing thermal efficiency. Longer styles may bunch behind the knees and restrict movement.

If you still want this type of clothing, choose shorter, athletic-cut versions with minimal seams, quick-dry fabrics, and no mesh liners that could create additional pressure points.

Compression Shorts/Underwear

Compression shorts support muscles and help with moisture build-up.

The graduated compression technology in premium versions can improve blood circulation during long sessions. These purpose-built undergarments feature flatlock seams positioned away from potential pressure points, antimicrobial treatments to prevent odor development, and strategic ventilation zones to manage moisture.

The body-hugging nature of compression gear integrates naturally with the similar pressure profile of a properly fitting wetsuit.

Rash Guard with Briefs

This combination works for upper and lower body protection.

The rash guard component protects the torso and arms during paddling movements. The athletic briefs support and protect without excess material that could bunch or gather. This pairing is easily customizable to different conditions: you can choose different rash guard weights and sleeve lengths, from lightweight, short-sleeve versions for warm water to thermal, long-sleeve options for colder conditions.

Key Factors Influencing Your Choice

Water Temperature

Cold Water (Below 60°F/15°C)

Specialized thermal rash guards with technologies like hollow-fiber insulation, infrared heat reflection, or titanium-infused fabrics can keep your core temperature steady. Neoprene shorts with sealed seams provide additional millimeters of insulation for your core region, where you need to stay warm.

Full wetsuit liners with brushed interiors add a thermal boundary layer that traps and recirculates body heat.

Moderate Water (60-70°F/15-21°C)

These middle-range temperatures offer the most flexibility in terms of undergarment selection.

Standard-thickness rash guards insulate enough to prevent overheating. Personal comfort and activity type are often the deciding factors under these conditions.

Longer sessions require more comprehensive coverage to prevent the gradual cooling effect, occurring even in moderate temperatures. The seasonal transition periods (early summer or late fall) often fall into this temperature range, making layering the perfect choice.

Warm Water (Above 70°F/21°C)

In tropical or heated conditions, the primary concern shifts from heat retention to not feeling overheated. Minimal undergarments let your body's natural cooling system function.

Many experienced warm-water divers prefer going without undergarments entirely in these conditions, while others opt for the thinnest possible rash guards primarily for chafe protection rather than insulation. The wetsuit is often thinner in these environments (2-3mm versus 4-6mm for colder conditions).

Activity Type

Surfing

Surfers want flexibility across the shoulders and upper back, which means minimal restriction in these areas. The repetitive paddle motion commonly causes underarm and chest chafing, which means undergarments should protect them.

Diving

Water pressure increases with depth, compressing neoprene and reducing its insulation value—a 5mm wetsuit might effectively provide only 2mm of insulation at 30 meters depth. This compression effect means you need to have effective undergarments.

When you dive, your movements are slow and limited: you don’t generate enough heat through muscle activity, which means you rely on the insulation from your wetsuit and undergarments. Divers often like full-coverage options that protect against the cooling effect of water circulation through the suit, particularly around entry points at wrists, ankles, and neck. ,

Paddle Sports

Activities like kayaking, stand-up paddleboarding, and outrigger canoeing involve continuous, repetitive upper body movement with particular pressure on specific contact points. Also, paddling means staying seated, creating pressure zones along the lower back and posterior.

Undergarments for these activities often feature reinforced panels in high-friction areas like the underarms and inner thighs.

Duration of Activity

Short Sessions

For brief water encounters lasting under an hour, the cumulative effects of minor irritations or temperature regulation issues rarely become significant problems.

Quick recreational outings give you more freedom regarding undergarments. The body can tolerate suboptimal conditions for limited periods without notable discomfort or performance impacts.

If you only go for shorter sessions, you can prioritize convenience and simplicity, rather than insulation.

However, extreme temperature conditions require the right undergarments for basic safety and comfort, even for short sessions.

Extended Sessions

Marathon surf sessions, multi-dive days, or long-distance paddling expeditions amplify every minor irritation into potentially session-ending discomfort. What begins as slight friction in the first hour can develop into painful skin abrasion as time passes.  

Extended exposures require proper chafe protection strategies, often with anti-chafing balms or lubricants and appropriate undergarments. During long sessions, the body’s energy reserves are depleted, which means the body doesn’t generate heat.

Consecutive hours in the water also test the durability and position-retention of undergarments. All these mean you should invest in warm, snug undergarments that fit like a glove under the wetsuit.

Wetsuit Ownership vs. Rental

Owned Wetsuit

If you own your wetsuit, it develops a custom fit to your body over time, with neoprene adapting to your proportions and movement patterns. This personalized compression profile interacts differently with undergarments compared to the generalized fit of rental equipment.

Owning a wetsuit means you have full control over your hygiene. You can even opt to wear nothing underneath it.

Rental Wetsuit

With rentals, hygiene is the top consideration.

Rental suits have already been worn by numerous individuals, which means you need protective barriers between your skin and the neoprene.

Rental wetsuits have standardized sizing, which can create unusual pressure points or abrasion zones that require additional protection. Rentals often come in specific thicknesses; undergarment options matter because they provide the extra insulation you need if the rental wetsuit doesn’t have the necessary thickness.

Personal Comfort & Modesty

Changing Situations

The logistics of changing into and out of wetsuits vary across different environments, from private changing rooms with shower facilities to exposed beach parking lots with minimal privacy.

The garment you choose impacts your changing experience, particularly in public settings. Full coverage options allow for more modest transitions, while minimal undergarments might necessitate changing robes, towel techniques, or other privacy solutions.

You also want to consider any pre-session preparation and post-session care. Some facilities let you rinse your wetsuit and undergarments, while others might require traveling home in damp conditions, affecting your choice of undergarments.

Personal Preference

Beyond purely technical considerations, what you need to wear depends on individual choices and comfort preferences.

Some individuals dislike minimal coverage options regardless of their technical merits, while others find full coverage restrictive or distracting.

Materials Considerations

Avoid Cotton

Despite its comfort in dry conditions, cotton is problematic when wet, as it absorbs up to 27 times its weight in water and holds this moisture against the skin.

This water retention increases overall weight, reduces thermal efficiency, and develops an abrasive texture that accelerates skin irritation during movement.

Cotton also takes time to dry, and if not washed and dried properly, it could harbor bacteria and unpleasant odors. Cotton blends should generally be avoided for wetsuit underlayers, as they retain many unwelcome characteristics even when mixed with synthetic fibers.

Prefer Synthetic/Technical Fabrics

Materials like polyester, nylon, spandex, and various blends manage moisture superbly through their hydrophobic properties that minimize water absorption and maintain structural integrity when wet.

Advanced technical fabrics sometimes include antimicrobial treatments that prevent bacterial growth and reduce odors and skin irritation.

Synthetics stretch enough so they don’t deform and keep their position even during extended sessions.

The Right Thing to ear under a wetsuit

So, what do I wear under a wetsuit?

You need to consider insulation and the type of activity you will be doing. Don’t forget the temperature of the water and your personal choices regarding comfort and practicalities. There are many options and combinations of clothes to wear under your wetsuit. When in doubt, our Divers Supply staff is always happy to help you choose the best choice for your needs.