Fans will recall (for various reasons) James Bond trading his tuxedo for a wetsuit in Thunderball (1965). In the course of his investigation against SPECTRE, Bond utilizes a nearly unbelievable gadget - an underwater camera.
The prototype used in filming was known as the 'Calypso-Nikkor'; the collective invention of Belgian engineer Jean De Wouters and Nikon. Designed for use by Jacques Cousteau, the camera became known as the 'Nikonos' line, and was the first widely-produced underwater camera. But James was going to need more than quality photos against his opponents.
He'd also need propulsion, in the form of a speciall- designed scuba tank equipped with a jet engine and headlight (for safety). Underwater propulsion had been used as early as WWI, but a portable Diver Propulsion Vehicle of the size and efficiency of Bond's wasn't seen until 1969, when Ralph Osterhout demonstrated his MK I for the US Navy.
Now versions of the DPV are available for rental from most major diving operations, and online for as low as USD $300. They may not resemble James' dangerous and inefficient scuba tank, but are popular enough to warrant an annual Grand Prix in South Florida.