Wetsuit buying guide: thickness, fit and cost
A wetsuit keeps you warm only if it fits. Here's how to match thickness to water temperature, decode 5/3mm numbers, and what each type really costs.
A wetsuit is the piece of gear that decides whether a dive is blissful or miserable. Too thin and you shiver; too thick and you overheat and fight to move; badly fitting and it floods, defeating the point entirely. The good news is that the rules are simple once you understand thickness and fit.
How a wetsuit keeps you warm
A wetsuit traps a thin layer of water against your skin, which your body warms and the neoprene insulates. That only works if the suit fits snugly — a loose suit flushes cold water through on every movement and you stay cold no matter how thick the neoprene is. Fit comes first, thickness second.
Reading the thickness numbers
You'll see numbers like 3mm or 5/3mm. A single number is uniform thickness; two numbers mean thicker neoprene on the core (warmth) and thinner on the limbs (flexibility). As a rough guide to water temperature:
- Shorty / 2mm — very warm tropical water; short legs and arms, minimal protection.
- 3mm full — warm tropical and Mediterranean summer diving; the most common travel suit.
- 5mm full — temperate and cooler seas; a versatile workhorse for many divers.
- 7mm semi-dry — cold water; thicker neoprene with better seals to limit flushing.
- Drysuit — cold and very cold water; keeps you dry entirely and needs separate training.
Match the suit to the water, not the air
Surface air temperature lies. A tropical island can have surprisingly cool water at depth or in certain seasons. Ask the local operator what thickness divers actually wear before you assume a shorty is enough.
Fit: the part shops rush
A good wetsuit feels firm everywhere with no loose pockets at the lower back, knees or armpits, but doesn't restrict your breathing or shoulder movement. Sizing varies a lot between brands, so try before you buy where you can. Women's and men's cuts differ for good reason — a suit cut for the wrong shape will never seal well.
Shorty vs full vs two-piece
A shorty is light and easy for warm water. A full suit covers arms and legs for warmth and protection from stings and scrapes. Two-piece systems (a jacket plus long johns) layer up for cold water and let you mix thicknesses. Choose by your typical water, not the warmest dive you might ever do.
What a wetsuit costs
Prices climb with thickness, seam quality and features. The tiers below are typical category ranges, not specific products — compare live verified prices on DiveCost before committing.
| Shorty / 2mmWarm-water and travel; minimal coverage. | €50–€110 |
| 3mm full suitThe common all-rounder for tropical and summer diving. | €90–€200 |
| 5mm full suitTemperate water; better seams and flexibility. | €150–€300 |
| 7mm semi-dryCold water; thicker neoprene and sealing. | €250–€500 |
| DrysuitCold-water diving; needs separate certification. | €800–€2500+ |
| Typical first wetsuit | €100–€250 |
Drysuits are a different category
A drysuit isn't just a warmer wetsuit — it's a different system with its own training, undergarments and maintenance. Only go there if you genuinely dive cold water regularly; for everyone else, a good 5mm or 7mm is plenty.
Buy or rent?
Wetsuits sit in the middle on cost, and rental suits are the gear divers most often dislike — worn neoprene, awkward sizing and hygiene concerns. If you dive a consistent water temperature and a few times a year, owning a suit that fits is a big comfort upgrade. If you travel to wildly different climates, renting the right thickness on-site can still make sense.
Weigh this against the full rent vs buy picture, and complete your soft kit with the right mask and fins. Planning a trip? See what's included on Makadi Bay and Dahab.
Bottom line: choose thickness for your real water temperature, prioritise a snug fit above brand or features, and don't buy a drysuit unless cold-water diving is genuinely your thing. A well-fitting 3mm or 5mm covers most divers for most trips.