Matching neoprene to the water
A wetsuit keeps you warm by trapping a thin layer of water that your body heats, while the neoprene’s gas bubbles slow heat loss. Thicker neoprene insulates better but is stiffer. The right thickness depends mainly on water temperature, then on your activity, the wind and how sensitive you are to cold.
Surfing and paddling
| Water temperature | Suggested gear |
|---|---|
| 75 °F (24 °C) and above | board shorts or rash vest |
| 72 to 75 °F (22 to 24 °C) | neoprene top or 1 to 2 mm shorty |
| 66 to 72 °F (19 to 22 °C) | 2 mm shorty or 3/2 spring suit |
| 61 to 66 °F (16 to 19 °C) | 3/2 mm full suit |
| 55 to 61 °F (13 to 16 °C) | 4/3 mm full suit, boots optional |
| 50 to 55 °F (10 to 13 °C) | 5/4 mm with 3 mm boots |
| 45 to 50 °F (7 to 10 °C) | 5/4 mm hooded, 5 mm boots, gloves |
| below 45 °F (7 °C) | 6/5 mm hooded, 7 mm boots, thick gloves |
The two numbers give the torso thickness first, then the arms and legs.
Swimming and triathlon
Swimming wetsuits use thinner, more flexible neoprene on the arms and add buoyancy. Race rules limit thickness to 5 mm. World Triathlon bans wetsuits for age-group athletes above 24.5 °C (76.1 °F), and USA Triathlon makes age-groupers who wear one above 78 °F (25.6 °C) ineligible for awards. Below about 60 °F (16 °C), add a neoprene cap and keep swims short.
Scuba diving
Divers barely move, spend long periods in the water and lose insulation as the neoprene compresses at depth. They need more than surfers: 3 mm in tropical water, 5 mm from about 64 to 75 °F (18 to 24 °C) and 7 mm or a semi-dry below. Under 50 °F (10 °C), a drysuit is the safer choice.
Worked example
At 60 °F (15.6 °C), a surfer needs a 4/3 mm full suit, and boots are optional. A diver at the same temperature should choose 7 mm, and a triathlete a full swimming wetsuit with a neoprene cap.
Fit matters as much as thickness
A loose suit flushes cold water through and loses most of its warmth. It should feel snug everywhere without restricting breathing, with no gaps at the lower back or armpits.