Under the dry suit, which underlayer is recommended for warmth?

• A. Cotton undershirt
• B. Wool thermal top
• C. Polyester base layer
• D. Thermal underwear

Answer: (D)

Under a dry suit, you want a base layer that stays close to your skin, wicks moisture away, and provides insulation. Thermal underwear is designed for this exact role. It acts as the insulating layer directly against your body while moving sweat away so you don’t chill inside the suit. Cotton undershirts, in contrast, soak up moisture and lose their insulation when wet, making you colder. A wool thermal top is a great warmth option, but the term thermal underwear captures the intended base-layer function—a lightweight, snug layer that keeps you warm and dry under the dry suit. A polyester base layer can work too, but the key idea is a dedicated moisture-wicking, insulating underlayer, which thermal underwear represents.