First, a few words about wetsuits. They work by trapping a thin layer of water next to the skin (hence the name, "wetsuit"). Body heat warms that layer, and the neoprene suit then keeps it warm through its natural insulation. At least, for a while. A lot of thrashing aroundswimming, for instancetends to push the warmed water out of the suit and lets cold water in. But in cold waters like those up in Maine and places, a good wetsuit should keep a swimmer comfortable for 45 minutes to an hour.
As to the type of suit, she'll clearly want a full-body suit, one with long arms and legs and a hood (as opposed to the armless "shorties," or armless but full-leg "farmer john" suits). As for the thickness of the neoprene suit, that's open to debate. Many wetsuits are used for scuba diving, and water pressure can compress a wetsuit and reduce its insulation. That's much less of an issue for surface swimming. So I'd say her suit should be at least a quarter-inch thick (six millimeters), and three-eighths of an inch (seven millimeters) is perhaps better.
Prices for wetsuits can vary widely, depending on thickness and quality of construction. Gas-blown neoprene, for instance, lasts longer than chemically-blown. And a suit that is glued and blind-stitched will outlast one that is only glued and taped. Expect to see prices of $100 to $300 for most full wetsuits.
Some good examples of high-quality wetsuits include the Henderson Premium Neoprene Full Jumpsuit, which is available in a dual-density model with five- and seven-millimeter neoprene for $220 (www.hendersonusa.com). Body Glove makes a full seven-millimeter suit for $260a hood adds another $65 (www.bodyglove.com). On the lower end, Divers Direct sells a six-millimeter womens Farmer John suit for $60, with another $60 for a six-millimeter jacket (www.diversdirect.com).
The most important thing is fit. A loose wetsuit will let cold water slosh inside, greatly reducing effectiveness. It should be snug but not binding, with no big pockets of air next to the skin.
Check out Outside Online's Gear Blog archives for reviews of more wetsuits and surf gear.