The warmth of a wetsuit largely depends on the thickness of its neoprene. Measured in millimeters (mm), a thicker suit will generally keep you warmer. However, a thicker suit will also weigh more and be less flexible, resulting in greater paddling fatigue and reduced performance. The goal is to choose a suit that is not unnecessarily thick for your local conditions.
To achieve a balance between warmth and performance, most wetsuits use a combination of neoprene thicknesses. Thicker panels are generally used in the chest, back, and lower body, while thinner panels are used through the arms and shoulders for greater flexibility and easier paddling. A suit’s particular combination of neoprene thickness is reflected in the name of the suit itself. For example, a “4/3mm” wetsuit uses both 4mm and 3mm neoprene. A “2mm” wetsuit is made entirely of 2mm neoprene. The thickness we list here refers only to the thickest neoprene used in the suit. More detailed information on the thicknesses used and their placement is listed below.
Keep in mind that additional features such as advanced seam construction, insulated lining, and hoods greatly impact the warmth of a wetsuit. The presence of these features can compensate for the reduced warmth of thinner neoprene, offering greater performance while retaining overall warmth. For example, a higher-end 4/3mm wetsuit with sealed seams and interior thermal lining will likely stay as warm as an economical 5/4mm wetsuit that does not have those features.
Chest Zipper - By removing the back zipper, chest-zip suits eliminate virtually all back flushing, enhance collar comfort, and allow unrestricted flexibility across the back torso for paddling.
In a perfect world, wetsuits would be seamless. Until then, the goal is to make seams as light, flexible, durable, and impermeable to water as possible. While each brand has its own lingo, there are four basic seam constructions on the market: flatlock; glued and blind stitched (GBS); glued and blind stitched with taping; and liquid rubber seam seal.
Glued, Blind Stitched, Fully Taped - A durable, flexible, and highly waterproof seam construction where two panels of neoprene are glued together end-to-end and then blind stitched. Stitches are visible on the seam exterior but do not protrude through to the interior, reducing sew-through holes and water entry. A thin strip of soft, waterproof, and highly flexible tape is then fused over the interior side of seam throughout the suit, providing increased waterproofness and durability.
Most cold water suits now include an insulating interior jersey lining made from a variety a materials. Its purpose is to wick water away from the skin while retaining body heat. The thermal lining is typically placed on the chest and/or back core panels to retain core body heat. On higher end suits, it is often extended throughout the torso and down through the thighs.