Water conducts heat away from our body 20 times faster than air. This is but one of the reasons that exposure protection is needed for people planning to engage in watersport activities. Excessive heat loss can lead to a dangerous condition called hypothermia. One can easily imagine this happening in cold water but don't fool yourself, even seemingly warm water can lead to this condition. Thermal protection is a "must" for those engaging in snorkeling. Exposure protection is not solely based on water temperature. It can also include protection against ultra violet rays as well as accidental interaction with certain types of marine life.
Knowing about the different types of exposure protection available will help the snorkeler determine what they need in the way of thermal protection. Exposure suits can be broken up into 4 different categories; Skins, Wetsuits, Semi-dry suits and dry suits. They are usually referred to either warm water or cold water suits with the semi-dry and the drysuits leaning heavily to the cold water. Since snorkeling activities are normally done in warm water destination, this article's intent will be to address exposure protection suitable for warm water environments.
Warm water exposure protection can include lycra body suits often referred to as "skins" or "rash guards" as well as neoprene wetsuits of various thicknesses. The temperature of the water is the determining factor as to what type of thermal protection is needed. Use the following temperatures as a general guide:
Water that is 80 degrees and warmer requires very little thermal protection such as a lycra jumpsuit or a .5 mm thick wetsuit.
Water temperature between 72 degrees to 80 degrees need at least a 2mm wetsuit shorty.
Water temperatures between 65 degrees to 72 degrees, a full body wetsuit 3mm or thicker.
Water temperatures ranging between 60 to 65 degrees 5mm or thicker.
Water temperatures between 50 to 60 degrees full wetsuit 6.5mm to 7mm.
Anyone planning to snorkel in water colder than 50 degrees should really consider getting psychological counseling. Seriously, a drysuit would be required.
Now let's look at the break down of the different suits themselves. Skins can be made of nylon, lycra, polyester, spandex, polyolefin and combinations thereof. They are usually found as full body jumpsuits or as separates consisting of a short or long sleeved top & shorts often called rash guards. As stated previously these suits provide very little thermal insulation. They make up for it though by offering more protection from ultra violet rays and jellyfish stings. Because of their elasticity they are usually unisex in sizing. Those with polyolefin work well to wick water & perspiration away from the body while out of the water. Snow skiiers often wear these beneath their clothing. Scuba divers often put skins on prior to getting into a wetsuit. This not only adds another layer of insulation, but also makes getting into a thicker wetsuit a lot easier. The long sleeved jumpsuit style usually has with thumb loops at the wrist & stirrups at the ankles which keep the suit from bunching.
Wetsuits afford the snorkeler a lot of the same benefits as a skin but the neoprene rubber dramatically adds to the thermal insulation value. Wetsuits are not designed to keep you dry. What they do is create a barrier which does not allow water through the material itself. Water does however get into the suit but instead of your body trying to heat up the entire lake or ocean, it traps the little bit of water that does get inside and heats that up. The wetsuit does not create heat. It slows down the heat loss. In order for a wetsuit to work effectively it must fit well. If it is baggy anywhere then it will not effectively trap the water. Most areas of concern are the armpit and crotch areas.
Wetsuit designs and materials have seen some dramatic changes in the last 25 years. One of the most dramatic was the introduction of a stretchier neoprene. Companies started using the stretchier neoprene in strategic places on their wetsuits. One company, Henderson, has a complete line of suits made entirely of this stretchier neoprene. They call it Hyperstretch and though slightly more expensive than regular neoprene, it is worth every penny. And from this person's point of view, it is one of the most comfortable suits on the market.
Wetsuits are made in different thicknesses. Common ones seen today are the .5mm, 2mm, 3mm, 5mm, 6.5mm and 7mm. Many manufacturers use a combination of thicknesses using thinner neoprene in areas such as the neck, elbows, forearms, back of the knee and the lower leg. Snorkelers rarely require anything thicker than a 5mm suit.
The three basic suit designs are the shorty, one piece jumpsuit and the 2 piece. The shorty is usually a short sleeved suit with either a front or back zipper and the legs rarely go lower than mid thigh. The one piece jumpsuit style is usually long sleeved with a front or back zip and the legs ending at the ankle bone. The two piece style is usually referred to as a jacket and farmer john (for men) or farmer jane (for women). The jacket is usually long sleeved with a front zipper and the farmer john or jane is reminiscent of a pair of farmer's overalls. It is a rare thing to see a snorkeler in a the two piece wetsuit style and many opt for either a shorty or one piece jumpsuit. Wetsuits with a back zipper have a tendency to be more user friendly with respect to self donning and doffing.