For general open water swimming there is no maximum thickness specified. A 5mm thick chest and torso panel is widely regarded as the norm. It provides excellent buoyancy and is sufficiently warm in colder water. The thickness limit for any wetsuit used in a triathlon is 5mm. Only the main floatation panel of the wetsuit (chest and torso) is generally 5mm. The other panels, e.g. arms, back of the legs, etc, vary in thicknesses ranging from 1.5mm to 3mm. These areas are less crucial to body flotation and offer more flexibility.