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.
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.
Flatlock - A durable, breathable, and economical seam construction where two panels of neoprene are overlapped and stitched together using a flatlock stitch. Flatlock seams are often found on warmer water suits and neoprene tops where absolute waterproofing is not critical or necessarily desired.
100% UltraFlex DS - Super flexible, soft Neoprene that provides 4-way stretch for unrestricted movement in any direction.
UPF 50+ - Don't Get Burned! O'Neill's Ultraviolet Protection Factor of 50+ provides maximum shielding from the sun to keep you burn and cancer-free.
FlatLoc Seams - A breathable, overlapping flatstitched seam. Non-chafing and super durable. Great for warmer conditions.