Antique Diving Helmet US Navy Mark V Deep SCA| Anchor Engineering Helmet

A diving helmet is a rigid head enclosure with a breathing gas supply used in underwater diving. They were worn mainly by professional divers engaged in surface-supplied diving. The upper part of the helmet, known colloquially as the hat or bonnet, may be secured to the diver or diving suit by a lower part, known as a neck dam, breastplate, or corselet, depending on the construction and regional language preferences.