Wetsuit vs Drysuit: Where the Crossover Actually Is

A wetsuit lets a thin layer of water in and warms it with your body. A drysuit keeps all the water out and insulates you with an undergarment and a layer of gas. That difference decides everything else: how warm you stay, how much lead you carry, how many buoyancy devices you are flying at once, what can go wrong, and whether you need another certification card. The temperature where most divers make the switch is around 55 F, and the sentence that matters most on this page is that the drysuit course comes before the drysuit.

How does each suit actually keep you warm?

A wetsuit works by controlling water rather than excluding it. Closed cell neoprene is foam full of nitrogen bubbles, and those bubbles are the insulation. The thin film of water that gets inside warms to something near skin temperature and stays there, provided it stays there. The suit fails when it flushes, which is when new cold water enters at the neck, wrists or ankles and replaces the water you spent energy heating. That is why fit matters more than thickness up to a point, and why a loose 7 mm suit can be colder than a well fitted 5 mm.

A drysuit excludes water entirely. Seals at the neck and wrists and a waterproof zip keep the inside dry, and the warmth comes from an undergarment plus the gas layer around it. Because gas is a far better insulator than water, a drysuit reaches temperatures a wetsuit cannot approach, and it does it without needing to be tight. It is also modular: change the undergarment and you change the suit's temperature range without buying another shell.

Neoprene has one more property that shapes the comparison. It compresses under pressure, so a 7 mm suit at 100 feet is thinner, less buoyant and less insulating than the same suit at the surface. The diver gets colder as the dive gets deeper, and buoyancy changes as they descend. A shell drysuit does not compress in the same way because you add gas to it as you go down, which is precisely the thing that makes it a second buoyancy device.

At what temperature should you switch?

Around 55 F is where the crossover sits for most recreational divers. That is not a hard boundary, because cold tolerance varies more between people than almost any other variable in diving, but it is where the arguments change sides. Above it, adding neoprene still works. Below it, adding neoprene stops working and starts restricting you.

Three things push you one step warmer than the chart suggests: repetitive dives, long dives and current. Doing three 50 minute dives in 62 F water is a genuinely different thermal problem from doing one, because you never fully rewarm on the surface. So is a dive spent finning against a current, which sounds like it should warm you and mostly does not once the exertion stops.

In the 50 to 58 F band a 7 mm semi-dry is the honest middle answer, and a Cressi Fast Lady 7mm Wetsuit or an XCEL Polar Hydroflex 8/7/6/5mm Scuba Fullsuit with its graduated thickness will get many divers through a season there. Below 50 F, a drysuit stops being a luxury. Work your own numbers with the wetsuit thickness calculator and cross check against the thickness chart.

Whatever thickness you land on, cover the head. An uncovered head is a large share of total heat loss, and a Dizokizo 3mm Neoprene Dive Hood is the cheapest warmth per dollar in diving. XUKER 3mm Neoprene Five Finger Dive Gloves and a decent pair of Phantom Aquatics 5mm Hard Sole Dive Boots matter for the same reason, because cold hands end dives long before a cold core does.

Why does a drysuit need its own certification?

Because it is a second buoyancy device, and diving it is a different skill rather than a different garment. On a wetsuit dive you manage one gas space with one inflator. On a drysuit dive you manage two, and they interact.

The specific failures the course exists to teach are all real and all fast. A stuck inflator adds gas continuously and will run away with your ascent if you do not disconnect the hose. Gas in the suit migrates to the highest point, so a diver who goes feet up finds the gas in their boots, which makes the feet up condition worse and can invert them into an uncontrolled ascent. A flooded suit turns a warm insulating layer into cold, heavy water and a serious buoyancy problem. Seals fail, zips fail, and both can fail at depth.

None of those failures are exotic and none of them are unmanageable, which is exactly why they are trained rather than improvised. The course is usually a day of theory and pool work plus two open water dives, and it is the cheapest part of drysuit diving by a wide margin. Take it before you buy the suit, because a course dive in a rental suit will also tell you which style you actually want.

How does weighting change between the two?

A great deal. A wetsuit adds buoyancy in proportion to its thickness and loses it with depth as the neoprene compresses, so a 5 mm full suit typically needs 8 to 10 percent of body weight in lead as a starting point, and a 7 mm suit with a hood around 10 percent.

A drysuit starts at roughly 10 percent of body weight plus another 4 to 8 lb, and the range is wide because the undergarment drives it. A thin thermal layer traps far less gas than a heavy insulating one, so changing undergarments changes your weighting. That is not a one time calculation you write on a slate and keep forever.

In both cases the number is a starting point and the weight check is the real answer. Do it at the end of a dive with a near empty cylinder: float at eye level with an empty BCD, hold a normal breath, and sink slowly on the exhale. In a drysuit, vent the suit down to a minimum first so you are checking your lead rather than your gas management. The weighting and buoyancy calculator gives you the starting figure and the buoyancy and weighting guide covers the check itself.

What does each one actually cost to own?

A good wetsuit is a few hundred dollars. A Cressi Fast 5mm Wetsuit covers most temperate diving, a Henderson 3mm Thermoprene Pro Men's Back Zip Jumpsuit is the comfortable warm to temperate option, and a Bare 5mm Reactive Wetsuit is what you buy when you want a 5 mm to behave like a warmer suit. Maintenance is a freshwater rinse and a wide hanger. The hidden cost is replacement: neoprene loses loft with compression cycles, and a heavily dived suit is measurably colder after a few hundred dives even when it looks fine.

A drysuit is a different order of purchase. A Bare Aqua Trek Tech Dry Drysuit is a trilaminate shell of the kind most cold water recreational divers end up in, and the suit is only part of the bill. You also need undergarments, and a Sharkskin Men's Chillproof One Piece Undergarment is a common first layer that doubles as a wetsuit base layer and the warmest thing to wear on a boat between dives. Add seal replacement, occasional valve service and zip care over the life of the suit.

Cold water diving also puts pressure on the regulator. A sealed, environmentally isolated first stage rated for cold water, like the Scubapro MK17 EVO 2 / C370 Regulator System , is the sensible partner to a drysuit, because a free flowing first stage in 45 F water is a considerably more serious event than the same failure in the tropics. That is a real part of the cost of moving to cold water, not an upsell.

Over a decade the drysuit often wins on cost per year, because a shell suit outlives several wetsuits. It loses on flexibility, on travel weight, and on the number of things that can go wrong. The wetsuit roundup covers the thickness ladder if you decide the answer is more neoprene rather than a different category.

What is it like to actually dive each one?

A wetsuit day is simple. You pull the suit on, you get wet, you get cold slowly, and you get out. The suit does nothing during the dive except lose a little insulation as it compresses. Your buoyancy changes with depth as the neoprene squeezes, which is why you add air to the BCD going down and vent it coming up, and that is the whole of it.

A drysuit day has more moving parts. You add gas to the suit as you descend to stop the squeeze, you vent it as you ascend, and you are doing that alongside the same job on the BCD. Most drysuit divers settle into using the suit for comfort and the BCD for buoyancy, or the suit for everything on a light rig, and which approach you use is something to decide with an instructor rather than to invent.

The surface interval is where the drysuit wins outright. Getting out of the water dry, in a warm layer, with nothing clinging to you, changes a three dive day completely. Divers who have spent a season shivering on a boat in a wet 7 mm suit understand the appeal immediately, and it is a legitimate reason to buy one even in water a thick wetsuit could technically handle.

The cost is a longer list of things to check. Seals, zip, valves, inflator hose and the state of your undergarment all matter before you get in, and a pre dive check that used to take a second now takes a minute. That is the honest ongoing tax of drysuit diving, and it is why the course exists.

Which should you buy?

Buy a wetsuit if your diving is in water above about 58 F, if you travel to warm destinations, if you dive occasionally rather than every week, or if you want one purchase that works without another certification. For the overwhelming majority of recreational divers a well fitted 3 mm or 5 mm suit is the correct and complete answer, and buying more suit than the water calls for makes diving worse rather than better.

Do not buy a wetsuit if your home water is below 50 F, if you are doing repetitive dives in the low 50s and finishing them cold, or if you are already at 7 mm plus a hood and still ending dives early. At that point more neoprene is restricting your movement and your breathing without buying you the warmth you need.

Buy a drysuit if you dive cold water regularly, you want to dive through the winter, you do long or repetitive dives where rewarming on the surface never happens, or you want to be dry and comfortable between dives on a boat. Buy the course first, dive a rental suit on it, and use that experience to choose between a shell and a neoprene drysuit.

Do not buy a drysuit if you dive twice a year in the tropics, if you are unwilling to do the certification, or if you want the simplest possible setup. Adding a second buoyancy device to a diver who is still working on buoyancy control makes both problems harder, and there is no shame in fixing the first one first. Gear never substitutes for training, and no suit extends the limits of a certification you do not hold.

Deciding on a specific model? We review the Henderson 3mm Thermoprene Pro back zip jumpsuit review and Cressi Fast 5mm wetsuit review in full.