Undersuits

Scuba undersuits are essential for divers using drysuits, providing an extra layer of insulation and comfort underwater. These undersuits are designed to be worn beneath drysuits, ensuring that divers remain warm and dry in even the coldest conditions. Made from high-quality, moisture-wicking materials, scuba undersuits help regulate body temperature, reducing heat loss and keeping the diver comfortable throughout their dive. Available in various thicknesses and styles to suit different diving environments, these undersuits offer flexibility and freedom of movement. Ideal for both recreational and technical divers, scuba undersuits are a crucial component of a complete diving setup, enhancing overall safety and enjoyment.

Undersuits

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Undersuits Guide: Warmth, Comfort - How to Choose the Right One

A good undersuit is an essential part of a drysuit system, playing a vital role in keeping you warm, comfortable, and protected during cold-water diving. The right undersuit helps regulate body temperature, manages moisture, and allows you to move freely underwater — making a significant difference to both safety and enjoyment.

At Dive Rutland, we stock and use undersuits from trusted manufacturers such as Fourth Element, Apeks, and other leading brands, chosen for their proven performance in UK and cold-water diving conditions.

Below is a guide to the main types of undersuits and how to choose the right option for your diving.

Thermal Undersuits

Thermal undersuits are designed to provide maximum insulation in cold water. Typically constructed from layered or fleece-based materials, they trap warm air around the body while remaining breathable.

These undersuits are ideal for winter diving, deeper profiles, or longer dive durations, and are often paired with thicker drysuits for optimal thermal protection.

Best for: Cold-water diving, winter conditions, and extended dive times.

Lightweight Undersuits

Lightweight undersuits offer a balance between warmth and flexibility, making them suitable for milder conditions or as part of a layered system. They provide insulation without excessive bulk, helping maintain good trim and ease of movement.

Many divers use lightweight undersuits year-round, adding extra layers when temperatures drop.

Best for: Warmer water, summer diving, or layering with additional insulation.

Base Layers

Base layers are worn directly against the skin and focus on moisture management and comfort. They wick sweat away from the body, helping keep you dry and warm throughout the dive.

While not usually worn alone in cold water, base layers are an excellent foundation for any undersuit system and help improve overall thermal efficiency.

Best for: All drysuit diving as a first layer, particularly on longer or repetitive dives.

Layering Systems

Layering undersuits allows divers to adapt insulation levels to suit water temperature, dive duration, and personal tolerance to cold. Combining a base layer with a lightweight or thermal undersuit offers flexibility across seasons without needing multiple single-purpose suits.

Layered systems also improve comfort between dives by managing moisture more effectively.

Best for: Divers who want year-round versatility and temperature control.

Key Features to Look For when choosing an undersuit, consider:

Thermal rating and insulation level
Breathability and moisture-wicking performance
Freedom of movement and stretch
Fit under your drysuit without restriction
Ease of donning and doffing

The right undersuit should keep you warm without compromising buoyancy control or mobility.

Choosing the Right Undersuit

There is no one-size-fits-all solution — the best undersuit depends on your dive environment, exposure protection, and personal comfort levels. UK divers, in particular, benefit from adaptable systems that perform well across changing seasons.

If you’re unsure which undersuit is right for you, speak to the team at Dive Rutland. As active divers ourselves, we are always happy to offer practical advice based on real-world diving experience.