Choosing the right wetsuit can make or break your dive—not just in terms of comfort, but also safety and energy levels. Too thin, and you’re shivering by the safety stop. Too thick, and you’re fighting buoyancy and overheating before you hit 10 metres.
Whether you're diving in the tropics, exploring cold UK waters, or somewhere in between, here’s what you need to know to pick the right wetsuit thickness for your dive conditions.
Understanding Wetsuit Thickness (and What Those Numbers Mean)
Wetsuits are measured in millimetres (mm) and typically come in combinations like 3mm, 5mm, or 7mm. You might also see dual numbers, like 5/4mm—this means the torso area is 5mm thick for warmth, while the limbs are 4mm for flexibility.
In short:
- Thicker = warmer, but less flexible
- Thinner = cooler, but easier to move in
Wetsuit Thickness by Water Temperature
Here’s a general guide to help match wetsuit thickness to the water temps you’ll be diving in:
| Water Temperature | Recommended Wetsuit Thickness |
|---|---|
| 28°C / 82°F and up | 1–2mm (shorty or dive skin) |
| 24–27°C / 75–81°F | 3mm full suit or shorty |
| 21–23°C / 65–74°F | 5mm full suit |
| 16–20°C / 50–64°F | 7mm full suit or semi-dry |
| Below 16°C / 50°F | Drysuit recommended (with thermal layers) |
- 28°C and above: In tropical waters, minimal insulation is key. A lightweight Waterproof Neoskin offers sun and stinger protection without bulk, or try the Fourth Element Xenos Shorty for a bit more warmth and comfort.
- 24–27°C: A 3mm wetsuit provides versatility for warm but not bath-like conditions. The Scubapro 3/2 Yulex is a sustainable option made from plant-based rubber, while the Xenos 3mm offers classic stretch and comfort.
- 21–23°C: As the water cools, a 5mm wetsuit becomes more appropriate. The Waterproof W7 5mm provides excellent insulation with a tailored fit, while the Yulex 5/4 keeps things eco-conscious without sacrificing performance.
- 16–20°C: These chillier waters call for something thicker. The Waterproof W7 7mm is built for colder conditions with superb sealing and comfort, or go for the Xenos 7mm for great flexibility and warmth. Or, if you tend to really feel the cold and want to stay extra toasty during your dive, the Scubapro Nova Scotia semi-dry is a fantastic option that offers drysuit-like warmth—without needing a drysuit specialty certification.
Note: Everyone feels the cold differently—if you tend to get chilly, opt for a thicker suit or consider layering.
Other Factors to Consider
Dive Duration & Depth - Longer and deeper dives can lower your core temperature, even in warmer water. Stay on the warmer side if you’re doing multiple dives a day.
Wind & Surface Conditions - Choppy surface intervals + wind = fast heat loss. A windproof jacket or neoprene vest between dives can make a huge difference.
Activity Level - Are you hovering still during a photo dive or finning hard on a drift? More movement generates more body heat.
Personal Cold Tolerance - Some divers are fine in 22°C with a 3mm, others are freezing in a 5mm. Know your comfort level and adjust accordingly.
Layering for Versatility
Not sure what to expect? Layering gives you flexibility:
- Add a neoprene vest, hood, or shorty over a 3mm for added warmth.
- Gloves and boots also help prevent heat loss—especially in colder water.
- In temperate waters, a 5mm with a hooded vest can be as warm as a 7mm.
Fit Matters More Than You Think
A poorly fitting wetsuit—no matter the thickness—won’t keep you warm. Look for a snug (but not restrictive) fit that prevents flushing (cold water entering and exiting the suit). Gaps = heat loss.
Pro tip: Try the suit on dry first, and make sure you can still move and breathe comfortably.
Travel Considerations
Thicker suits are heavier and bulkier, which can be a pain for baggage limits. If you’re heading somewhere warm, a 3mm or shorty is much easier to pack.
If you're diving in colder regions like the UK or northern Europe, it's worth investing in a properly fitted 5mm or 7mm—or a drysuit if you're going full cold water.
Final Thoughts
The “right” wetsuit thickness is personal—but water temperature is a great place to start. Think about your dive plan, location, and how you usually feel in the water. With the right suit, you’ll stay warm, safe, and focused on what matters: enjoying the dive.
👉 Want help choosing the perfect wetsuit?
Browse our full wetsuit range or reach out to the team—we’re happy to advise based on your next trip.
Click here for our handy guide on how to look after your wetsuit.
Need a hand choosing the right suit? 🤿 Whether you're unsure about fit, features, or what’s best for your next adventure, we’re here to help! Feel free to pop into Mike’s Showroom in Chiswick for expert advice and to try gear in person, or book a consultation online — we’re always happy to guide you through your options.
