There was only one Carmagnolle diving suit ever made and it sits, unused, in the Navy museum in Paris. In order to cope with undersea water pressure the helmet looks like a giant insect eye compound lens with 20, small, round, lenses, one of which screws open to allow the wearer some fresh air while being suited up.

This is the same helmet as the other version featured in this list, but without the welding visor. Its specifications are so rugged that the air intake looks like a motorbike manifold.

This is a Swiss made 2 piece helmet that opens up, therefore avoiding having to have an opening big enough to slide your head into. Its much smaller and more flexible than its one piece alternatives and so is favored by the military and extreme sports divers for use in places such as underwater caves.

This is a working helium/oxygen mix helmet based upon the all time classic US Navy Mark V helmet, but modified with a tank on the back to recycle some of the helium. Desco will sell you it for $10,000. When divers use a helium mix they sometimes have to wear headsets which adjust the pitch of their voices so that they can understand each other.

For some reason, this helmet, with its array of lenses, reminds us of the screw top aluminum containers you get in kitchens.

Although this is a round, space helmet shaped shaped design this helmet is a world apart from the deep sea versions. Made in Japan, this helmet allows people with no diving experience to walk in shallow water without the need to use a regulator or ordinary face mask.

This is a state of the art modern helmet, of the type worn by diviers working on sea oil rigs. The most noticeable feature is the optional welding screen attachment, for that most dangerous of underwater tasks.

Designed in the late 60s and still in use, the DESCO air hat is something of a design classic. It is still the preferred helmet for use in hazardous conditions.

Made in the late 30s one the distinctive features of this shallow water helmet, other than its lamp like shape, is the inclusion of a Bakelite telephone handset for communication with the surface.

A 1986 replica of an early 20th Century sponge divers helmet.

This late 40’s minimalist Russian helmet is a Platonic ideal of what a diving helmet should look like. Its what you might produce if asked to draw a diving helmet from memory.

This is a custom made $800 helmet based upon the type of thing that NASA astronauts would use for weightless simulation training in pools.

The Aqua Bell was a mass produced, toy like, shallow water diving helmet, produced in the 1970s. As of writing, someone is currently selling one on eBay.