Wetsuits are available in a range of thicknesses. The thicker the neoprene, the warmer the suit will be. For this reason, it's important to make sure you wear enough to keep you warm, but not enough to cause overheating. The most common thicknesses are 3-mm, 5-mm, and 7-mm. 3 and 5-mm suits are popular for warm water diving, while those in cold water usually prefer a 7-mm suit.