Abstract: A diving helmet including a uniquely designed three element structure and associated connecting and releasing means for quick bail-out, when, for example, the helmet's umbilical cord is damaged, tangled, or cut, to permit quick release and removal of the outer hard hat helmet. The system includes an inner dry hood with a facial opening framed with an oval, tongue-in-groove type seal along with a separate rigid protective outer helmet made up of a hat portion or hard casque and a mask portion with goggles, the two helmet portions being hingedly connected together (note FIG. 2). The hood seal is adapted to match and mate with the goggle mask assembly (note FIG. 3) sustaining the umbilical lines, gas regulators, window etc. to form a dry enclosure therebetween.