Abstract: A diver's helmet is retained on the diver's skull by curved retainer rods hinged to each side of the helmet. Connected to the hinged rods are rotary handles operated by the diver to rotate the rods under the jaw and base of the skull to retain the helmet, and rotated away from the diver's head to permit doffing and donning of the helmet. The retainer can be combined with a neck dam to clamp the elastic dam against the diver's jaw and skull to prevent ballooning of the neck dam and thereby prevent a change in buoyancy. When the retainer rods are hinged to helmet they act to retain the neck dam to the helmet.

Abstract: A head enclosing helmet structure is provided including a fluidtight front viewing window and a lower access opening for upwardly removably receiving the head of the wearer of the helmet therethrough. The outer surface portions of the helmet portions disposed about the lower access opening are generally cylindrical and an annular collar of deformably and compressible material is wedgingly removably receivable between the inner surfaces of the access opening of the helmet and the opposing neck surfaces of the wearer.