The Hydra Neoprene Drysuit is designed with cold water adventures in mind. With a close fitting, streamlined style, the Hydra is warm and flexible. High Density Neoprene (HDN) is used in critical areas throughout the suit. Compressed from 7mm to 4mm, HDN fuses the thermal protection of neoprene with a greater consistency of buoyancy throughout the dive. HDN is laminated with hardwearing fabric on the outside for excellent abrasion resistance, and smoother linings on the inside to increase comfort and aid donning.