What to wear under a wetsuit

What to Wear Under a Wetsuit: A Complete, Practical Guide

Wearing the right layers under a wetsuit can significantly improve comfort, warmth, hygiene, and performance. Whether you are surfing, diving, swimming, paddleboarding, or doing triathlons, what you wear (or don’t wear) under your wetsuit matters more than many people realize.

This guide explains what to wear under a wetsuit, when to wear extra layers, and what to avoid—based on water temperature, activity type, and wetsuit design.

Do You Need to Wear Anything Under a Wetsuit?

In most cases, you do not need to wear anything under a wetsuit. Modern wetsuits are designed to be worn directly against the skin to maximize thermal efficiency and flexibility.

However, there are situations where wearing something underneath is beneficial:

• Cold water conditions

• Long sessions (2+ hours)

• Rental wetsuits (hygiene)

• Sensitive skin or chafing issues

• Training or competition rules (e.g., triathlons)

Best Options to Wear Under a Wetsuit

1. Nothing at All (Skin Only)

Best for:

• Surfing

• Freediving

• Short sessions

• Warm to moderate water

Why it works:

• Best insulation (less water movement)

• Maximum flexibility

• No bunching or pressure points

Downside:

• Can cause chafing (neck, underarms, inner thighs)

• Less hygienic in rental suits

This is the most common and recommended option for experienced users.

2. Swimsuit or Bikini

Best for:

• Rental wetsuits

• Beginners

• Easy changing before/after sessions

What works best:

• Thin, tight-fitting swimwear

• No knots, ties, or thick seams

Avoid:

• Board shorts (cause bunching)

• Loose bikinis (shift under pressure)

This option offers basic hygiene and modesty without major performance loss.

3. Rash Guard (Top or Full)

Best for:

• Preventing rash and chafing

• Long surf or paddle sessions

• Sensitive skin

Material:

• Nylon / Lycra / Spandex blends

Benefits:

• Reduces friction

• Makes wetsuit easier to put on and remove

• Adds minimal bulk

A rash guard does not add warmth, but it significantly improves comfort.

4. Neoprene Base Layers (Thermal Undersuits)

Best for:

• Cold water diving

• Winter surfing

• Extended exposure

Common types:

• Neoprene shorts or vests

• 0.5–2mm thermal tops

• Full neoprene undersuits

Benefits:

• Noticeable warmth boost

• Improved core temperature

• Ideal for water below ~12°C / 54°F

Trade-off:

• Reduced flexibility

• Tighter fit required

This is the best solution for cold water, not regular swimwear.

5. Triathlon-Specific Layers

Best for:

• Open-water racing

• Training sessions

Typical choice:

• Triathlon suit under wetsuit

Why:

• Designed for swimming efficiency

• No water retention

• Easy wetsuit removal during transitions

This is standard practice in competitive triathlon settings.

What NOT to Wear Under a Wetsuit

Avoid the following, as they reduce performance or cause discomfort:

• Cotton underwear (absorbs water, causes chafing)

• Thick sports bras with padding

• Board shorts or loose shorts

• Clothing with zippers, hooks, or metal parts

These items interfere with water flow, stretch, and fit.

What to Wear Under a Wetsuit by Activity

Surfing

• Nothing, or rash guard

• Thin bikini bottoms (optional)

Scuba Diving

• Neoprene undersuit or thermal base layer

• Swimsuit underneath for hygiene

Freediving

• Nothing (for maximum seal and warmth)

Swimming / Open Water

• Swimsuit or tri suit

Cold-Water Sports

• Thermal neoprene layers

• Optional fleece-lined undersuits

Hygiene, Comfort, and Skin Protection Tips

• Rinse wetsuit after every use

• Use anti-chafe balm on neck and thighs

• Avoid body lotions before wearing

• Ensure correct wetsuit size (too tight = rash)

What you wear under the wetsuit should never compromise fit.

Final Recommendation

For most people and most conditions:

• Warm water: Wear nothing or a thin swimsuit

• Long sessions: Add a rash guard

• Cold water: Use neoprene thermal layers

• Racing: Wear a tri suit

The key principle is thin, tight, and purpose-built. Anything bulky, absorbent, or loose will work against the wetsuit’s design.