The Gill suit is an water-tight insulating suit used for swimming activities, layered with an Artificial Gill to extract oxygen from water. The suit are made of numerous layers of osmotic fabric, powered by the movements of the wearer, extracting oxygen from the water and passing it to the integrated oxygen rebreather. Bladders within the suit's layers automatically inflate with or bleed off oxygen as pressure changes, to keep the suit and diver neutrally buoyant. The rebreathers in gill suits can be fitted to use helium as a nitrogen substitute, greatly increasing the depth limits of the user. Thermal wiring in the suit's inner layers serves to keep the user warm even in the coldest water. Most Gill suits are fitted with numerous pockets, D-rings, and fitting straps, making them utilitarian and with little effort to make them fashionable.