Wiki Deep dive into Standard diving dress

Standard diving dress is the classic heavy, surface‑supplied suit consisting of a copper/brass helmet clamped to a watertight canvas suit, used historically for deep underwater tasks such as salvage, civil engineering, pearl diving and naval operations. Its core components are the helmet, air hose supplied from hand pumps or low‑pressure compressors (or integrated rebreathers in some variants), weighted chest, back and boots for negative buoyancy, a diving knife, and later a telephone for voice contact. Variants accommodated mixed gases and helium for greater depths and incorporated semi‑closed rebreathers; with appropriate breathing gases the equipment was employed to depths around 180 m (600 ft). Operations typically used the diver "heavy," walking on the bottom rather than free swimming.

The system evolved from the Deane brothers’ 1820s smoke‑helmet adaptation for underwater work and was perfected by Augustus Siebe, who produced a detachable, clamped helmet and full‑length watertight suit with valves that prevented flooding, creating the standard dress that revolutionized commercial and naval diving. Mid‑19th century innovations by Rouquayrol and Denayrouze added a demand regulator and the distinctive "pig‑snout" mask. Later developments produced three‑ and twelve‑bolt helmets (including the US Navy Mk V), gas recirculation and demand systems, and ultimately lighter stainless steel or fiberglass helmets that largely superseded the heavy copper gear.