When you dive, the Tasman Sea doesn't care how keen you are or how much you spent on your regulator. You can have the sharpest fins and a tank full of nitrox, but if your teeth are chattering so hard you can’t keep the mouthpiece in, the dive is over. That is the reality of diving in New South Wales. We aren't in the tropics. We deal with currents, thermoclines, and a seasonal shift that turns a pleasant shore bash into an endurance test. 

The choice between drysuits and wetsuits determines if you enjoy that second dive of the day when the wind is whipping off the water at Kurnell, or if you call it quits early. We aren't selling a fantasy of endless summer here. This is about the hardware you need to stay warm, safe, and functioning underwater. 

Understanding Thermal Protection for Scuba Diving 

Water is a thief. It steals heat from your body twenty-five times faster than air. You might stand in 20°C air and feel perfectly fine, maybe even a bit warm. Submerge your body in 20°C water, and your core temperature starts dropping immediately. The body responds by pulling blood away from your extremities to protect the vital organs. Your fingers get clumsy. Your thinking gets slow. This isn't just uncomfortable; it is dangerous. A cold diver uses air faster, fatigues quicker, and acts with less precision. 

In NSW, we don't have a single "diving temperature." You might hit a balmy 24°C at Fish Rock in February, or you might drop into a chilly 15°C patch at Shelly Beach in July. The gear that works for a shallow dive in summer will leave you shivering violently during a boat dive in winter. Scuba diving in NSW requires you to respect the local gradient. 

Typical NSW Water Temperatures 

If you only dive between Christmas and Easter, a wetsuit does the job. But if you want to see the Grey Nurse Sharks congregate in winter or catch the clearest visibility that cold water brings, you need to look at more serious diving gear for cold water. 

What Is a Wetsuit and How Does It Work? 

A wetsuit is a sponge. It is made of neoprene, a rubber foam filled with thousands of tiny nitrogen bubbles. These bubbles provide insulation. When you jump in, the suit allows a small amount of water to enter. Your body heat warms that thin layer of trapped water, and the neoprene prevents that heat from escaping into the ocean. 

The system works, but it has flaws. First, you are wet. If the water flushes in and out—down the neck seal or through a loose wrist cuff—you lose that warm layer and have to heat a new batch of cold water. That costs energy. Second, neoprene compresses. At the surface, a 7mm suit offers 7mm of insulation. Descend to 30 metres, and the pressure crushes those tiny bubbles flat. Your thick winter suit becomes as thin as a newspaper, offering almost no thermal protection exactly where the water is coldest. 

Wetsuits are the default for recreational divers. They come in various styles: 

What Is a Drysuit and How Does It Work? 

A drysuit is a shell. Unlike a wetsuit, it often offers zero thermal protection on its own. Its job is to keep the ocean out. You stay dry. The warmth comes from what you wear underneath—thermal undergarments, wool base layers, or specialized thinsulate jumpsuits. 

Because the suit is sealed at the neck and wrists (usually with latex or silicone), no water touches your skin. You are diving in a bubble of air. Air conducts heat poorly, which is great for you. More importantly, air doesn't compress the way neoprene foam does. If you feel the squeeze of the water pressure, you simply tap a valve on your chest to inject air from your tank into the suit. This maintains the loft of your undergarments, keeping you warm regardless of depth. 

Drysuits come in two main flavours: 

This gear changes the logistics of a dive day. You aren't stripping off a clammy, cold piece of rubber in a windy car park. You unzip your suit and step out in the dry clothes you were wearing underneath. For winter diving, this difference changes the entire experience. 

Drysuits vs Wetsuits: Key Differences 

The mechanics are different, and so is the feel. A wetsuit is simple: put it on, jump in. A drysuit is a system that requires management. You have an inflator hose connected to your tank, just like your BCD. You have to manage the air inside the suit to avoid a "squeeze" (where the suit sucks against your skin like vacuum packing) or a "floaty feet" situation (where air rushes to your boots and flips you upside down). 

Here is how they stack up directly: 

Choosing Based on Your Dive Conditions 

Decision fatigue is real, so let’s cut through the noise. You don't need a drysuit to look at a Weedy Seadragon in 5 metres of water in January. But you will regret not having one if you are doing a deco stop at 20 metres in August. 

Choose a Wetsuit If... 

Choose a Drysuit If... 

Drysuit Training and Considerations 

You cannot just buy a drysuit and jump off the boat. Well, you can, but it usually ends with you rocketing to the surface feet-first like a runaway Polaris missile. 

Managing the air bubble inside your suit adds a task to your dive. You need to learn how to vent air from your shoulder valve, how to recover from an inversion, and how to disconnect a stuck inflator valve. Buoyancy control changes. Many drysuit divers use the suit for buoyancy and only use their BCD as a backup or for surface flotation. 

At Frog Dive, we see this all the time. Divers buy the gear but skip the skills. Don't be that person. We run specific drysuit specialty courses that put you in a pool or shallow water to sort out your weighting and trim before you hit the open ocean. It’s about muscle memory. Once you crack it, the feeling of being weightless and warm is unmatched. 

Also, consider maintenance. A drysuit zipper is an expensive piece of engineering. If you jam it with sand or force it, you’re looking at a pricey repair. The neck and wrist seals are usually latex or silicone; they degrade over time and need replacing. It’s not a "chuck it in the shed" piece of kit. 

Gear Hire or Buy? What’s Best for You? 

This is the sticking point. Drysuits are an investment. A decent setup rivals the cost of a high-end computer or a full reg set. 

If you are curious but unconvinced, drysuit hire is the bridge. Renting allows you to test the difference without draining your savings. You can see if the extra buoyancy management annoys you or if the warmth is worth the hassle.