How to Choose a Wetsuit: Thickness, Fit, and Everything In Between

A wetsuit is one of the most personal pieces of gear you'll ever buy. Get it right and you barely notice it's there. Get it wrong and you spend your entire dive distracted by a neck that's cutting off circulation or arms that won't straighten fully.

The good news: choosing a wetsuit isn't complicated once you understand what actually matters. Here's a practical guide to finding the right one — and one tip that makes wearing it dramatically more pleasant.

Start With Water Temperature

Wetsuit thickness is measured in millimeters, and the right thickness is almost entirely determined by the water temperature you'll be diving in. Everything else is secondary.

Here's a straightforward guide:

Above 82°F (28°C+): You probably don't need a wetsuit at all — a full-coverage dive suit or dive skin provides enough thermal protection for most people in truly tropical water, plus sun and jellyfish protection.

77–82°F (25–28°C): A 1–2mm wetsuit or shorty works well. Enough to take the edge off without overheating on the surface. This is the range for much of the Caribbean, the Florida Keys in summer, and Indo-Pacific reef diving. Or, again, you may not need a wetsuit at all.

70–77°F (21–25°C): A 3mm full suit is the standard choice. Comfortable for most divers across a full dive day without becoming restrictive.

60–70°F (15–21°C): Step up to a 5mm. This covers temperate Pacific diving, the Florida Keys in winter, and much of the Mediterranean in shoulder season. Consider a hood if you run cold.

Below 60°F (15°C): A 7mm suit, drysuit, or semi-dry is the right call. Cold water pulls heat from your body faster than almost anything else in diving — don't underestimate it.

One important note: these are starting points, not rules. Individual cold tolerance varies enormously. Some divers are comfortable in a 3mm at 72°F; others need a 5mm. When in doubt, go one thickness warmer — you can always unzip at the surface.

Full Suit vs. Shorty

Full suit — covers arms and legs completely. Best for anything below 77°F, long dives, multiple dives in a day, or anyone who runs cold. Also provides the best protection against jellyfish contact and reef scrapes.

Shorty (also called a springsuit) — short sleeves and short legs, covering the core while leaving limbs largely exposed. Good for warm, calm conditions where you want some thermal protection without full coverage. Best for water 68°F and above. Less versatile than a full suit and offers limited jellyfish protection.

For most divers who travel to different destinations with variable water temperatures, a quality 3mm full suit covers the widest range of conditions. It's the most useful single wetsuit to own.

Wetsuit Fit: The Most Important Factor Nobody Talks About Enough

A wetsuit works by trapping a thin layer of water between the neoprene and your skin. Your body heats that water, and the neoprene keeps it there. This only works if the suit fits snugly. A loose wetsuit flushes cold water through constantly and defeats the entire purpose.

What good fit looks like:

• Snug against your skin with no sagging, bunching, or gaps at the armpits, crotch, or lower back

• Full range of motion in the shoulders — you should be able to extend your arms overhead without the suit pulling down, and give yourself a hug without feeling like the back will split.

• No gaping at the neck or wrists

• Slightly uncomfortable to put on (that's normal — neoprene stretches once on)

What bad fit looks like:

• Wrinkles or folds in the torso

• Pulling or restriction that limits shoulder or arm movement

• A collar so tight it restricts breathing or so loose it flushes constantly

• Excess material at the knees or elbows

Try a wetsuit on before you buy whenever possible. Sizing varies significantly between brands and even between suit lines within the same brand. Don't assume your size in one brand translates directly to another.

Neoprene Types: What the Marketing Actually Means

Not all neoprene is the same, and wetsuit marketing loves to make this confusing. Here's a quick translation:

Standard neoprene — petroleum-based, durable, widely available. The baseline for most recreational wetsuits. Nothing wrong with it.

Limestone neoprene — sourced from limestone rather than petroleum. More environmentally friendly, slightly more flexible. Brands like Patagonia and O'Neill have shifted to this.

Yamamoto neoprene — a Japanese-made limestone neoprene widely considered the premium standard. Warmer, more flexible, and more expensive. Common in high-end freediving suits.

Open cell vs. closed cell — this distinction matters most for freediving wetsuits, and it's worth understanding clearly.

Closed cell neoprene has a fabric lining on the interior (usually nylon or polyester). Water enters the suit, your body heats it, and that thin warm layer keeps you insulated. It's durable, easy to get on, and the standard construction for most recreational scuba wetsuits.

Open cell neoprene has no interior lining — raw neoprene sits directly against your skin. Two things work together to make it exceptionally warm: first, the exposed neoprene creates millions of tiny suction cups that grip your skin and form a near-watertight seal, preventing water from flushing through. Second, the neoprene itself is filled with tiny air pockets that significantly increase insulation — trapping warmth rather than letting it escape. The result is a suit that keeps you noticeably warmer than a closed cell suit of the same thickness. Open cell suits also tend to be more flexible and look sleeker in the water.

The tradeoff: they're more delicate, require lubrication (soapy water or conditioner) to put on, and need to be worn directly against bare skin to work properly. They're the preferred choice for serious freedivers and spearfishers who prioritize warmth and flexibility — and once you've tried one, it's hard to go back.

For recreational scuba, closed cell is the practical everyday standard. For freediving and spearfishing, open cell is worth the extra care.

The One Thing That Makes Getting Into a Wetsuit So Much Easier

Here's the honest reality of wetsuit diving: getting in and out of a closed cell wetsuit is annoying. A good-fitting suit is supposed to be snug, which means pulling it on — especially when you're warm, on a boat, with the sun beating down — is a full-body workout. Getting it off post-dive, when the neoprene is wet and clingy, is somehow worse.

The solution most experienced divers use: wear a thin, full-coverage base layer underneath.

A UPF 50+ dive suit worn under a closed cell wetsuit reduces friction dramatically, making the wetsuit slide on and off in a fraction of the time. It also means you're not standing on the boat deck in just a swimsuit while you wrestle with neoprene — you're covered, comfortable, and protected from the sun the entire time. When you peel your wetsuit off between dives or on the ride back to shore, you're already wearing something. No scrambling for a cover-up, no sunburn during surface intervals.

Plunge's UPF 50+ Dive Suits work perfectly in this role. Thin enough not to add bulk under a closed cell wetsuit, four-way stretch so they move with you at depth, and full sun protection for the moments above water when you're most exposed and least thinking about it.

Worth noting: open cell wetsuits are designed to be worn directly against the skin — that direct contact, combined with the air pocket insulation in the neoprene itself, is what makes them so exceptionally warm. A base layer isn't compatible with that construction, which is one of the genuine tradeoffs of going open cell. For closed cell wetsuits though, a base layer is a game changer.

One-Piece vs. Two-Piece Wetsuit Systems

Some divers — particularly cold-water and technical divers — opt for a two-piece system: a farmer john (sleeveless full-length bottom) plus a jacket top. This doubles the neoprene thickness on the torso without going to a single ultra-thick suit, which tends to be more flexible and easier to move in.

For recreational divers in warm to temperate water, a one-piece full suit is simpler and adequate. Two-piece systems are worth exploring if you're regularly diving below 60°F or find that thick single suits restrict your arm movement too much.

Sealed Seams, Zippers, and Other Details

Seam construction — flatlock seams (stitched flat) are durable but let some water through. Glued and blind-stitched seams (GBS) are warmer and more waterproof. For anything below 72°F, look for GBS construction.

Wrist and ankle seals — some suits have thin neoprene cuffs that seal out flushing at the extremities. Worth having on suits you'll use in cooler water.

Interior lining — some suits feature thermal lining panels in high-heat-loss areas (chest, kidneys). These add warmth without adding thickness and are worth looking for in 3–5mm suits used in cooler water.

What the Fish?!

The Chimaera: A Living Fossil With a Ghost's Reputation

The chimaera (Chimaeriformes) has been drifting through the deep ocean for roughly 400 million years — which means it was already ancient when the dinosaurs showed up. It belongs to a group called Chondrichthyes, the cartilaginous fish, making it a distant relative of sharks and rays. But while sharks got famous, the chimaera retreated into the deep and stayed weird in private.

Also called ghost sharks, ratfish, or rabbit fish depending on the species and region, chimaeras are genuinely unsettling to look at. They have large, flat heads with rabbit-like teeth fused into plates for crushing hard-shelled prey, enormous iridescent eyes built for near-total darkness, long whip-like tails, and a venomous spine in front of their dorsal fin. Their skin is smooth and scaleless, and in many species has a ghostly, translucent quality that makes them look less like a fish and more like something imagined.

Most species live at depths of 200–2,600 meters, which is why almost no recreational diver ever sees one. When they do appear on deep-sea camera footage, researchers describe them as moving with an eerie calm — slow, deliberate wing-like pectoral strokes, completely unbothered by the crushing pressure around them.

There are about 50 known species, ranging from the spotted ratfish of the Pacific to the plownose chimaera, with its bizarre fleshy snout extension used to detect electrical fields from buried prey. Scientists still know relatively little about their reproduction, lifespan, or behavior — the deep ocean keeps its secrets well.

The name "chimaera" comes from Greek mythology — the fire-breathing monster assembled from mismatched animal parts. Look at one long enough and you'll understand why.

Stay Salty

The right wetsuit makes cold water approachable and long dive days genuinely comfortable. Get the thickness right, prioritize fit over brand, and don't underestimate how much easier the whole experience gets when you've got a solid base layer underneath.