Exposure Protection / Wetsuits and Drysuits

Wetsuits keep you warm by doing two things: they keep the cold water off your skin as much as possible (reducing heat loss through convection) by minimizing water entry into the suit. Second, the tiny air bubbles in the neoprene create a dead air space, reducing heat loss through the suit itself. While any wetsuit with good seals performs the first function well, the second is influenced directly by the thickness of the suit: thicker suits lose less heat to the environment, keeping you warmer.

shorty wetsuit

Even diving in the tropics, you'll likely want a wetsuit of some kind. There are many different styles. "Shorties" (which don't fully cover the arms or legs) are the cheapest (often $40-$60 retail), but don't offer much warmth. "Fullsuits" (which do cover the arms and legs down to the wrists and ankles, respectively) are warmer, since they cover more of your body.

Wetsuits come in several thicknesses, usually stated in millimeters (mm). The thinnest are 1 or 2mm, while the thickest are usually 7mm. In warm tropical water, many divers use either a shorty or a thin full suit (3mm or so) if they plan on diving a lot. The effect of thermal heat loss is cumulative with many dives in a short time period, so you can get cold even in relatively warm water if it's below your body temperature. In cold water, like the California Coast, a 7mm wetsuit is the norm.

Cold-water (thick) wetsuits come in two main styles: a one-piece fullsuit, and a two-piece "jacket and farmer john". These are often worn with additional neoprene for added warmth: a hood or hooded vest along with boots and gloves. That often works in water as cold as about 50 degrees F. Any colder and you'd likely want a drysuit (if you can afford it).

fullsuit

Fullsuits (and two-piece combos) often retail for about $130-$300 for a typical suit. Suits made of something besides standard neoprene, like Henderson's "Hyperstretch" or "Instadry", cost more (sometimes a lot more). Some wetsuits are called "semi-dry", and offer improved seals at the neck, wrists, and ankles, to minimize water entering the suit. These are nice features, but you're still going to get wet.

A wetsuit must fit you well in order to keep you warm, and the limited stretch of the material means that not all suits will fit you well (even ones that seem like they should). It's best to try one on and make sure it is snug (but not overly restrictive) before buying one. Most dive shops have wetsuits in many styles, from several manufacturers, and it's worth trying on several before buying so you know the differences between them. Be aware that trying on wetsuits (especially cold-water wetsuits) can be hard work!

A drysuit works a little differently: the neck and wrist seals are excellent, and an integrated boot of some kind is included, so no water (in theory) gets into the suit while you're diving, keeping you dry. Thermal insulation is usually worn underneath, which can keep you warm even in very cold water. Drysuits have other advantages (and disadvantages), so talk to a shop owner or search around online to learn more. They cost a lot more than wetsuits: retail prices range from about $600 to $2000 (or more!)

Next page: Choosing Dive Boots and Gloves