Seaglide Personal Underwater Propulsion System (PUPS)[]
This technology is nothing new. Personal underwater propulsion devices have been around since the 20th century and have both civilian and military applications. They provide a fast and reliable means of transport for the exploration of underwater cave systems and the location of potential mining sites. However, these systems have come a long way since the early days of powered personal underwater transport when such devices were large, heavy and slow; today's personal underwater propulsion systems are much smaller, lighter and faster.
Conception[]
During the period of humanity's expansion into the greater galaxy and the subsequent rivalries between Earth-based paramilitary forces and independent colonial corporations, there was some concern among naval personnel that special operations teams would be limited by proven but ancient technology that hadn't changed much over the past three hundred years. If they were to be effective and efficient, each soldier needed their own PUPS unit in the event that the entire team couldn't leave the designated area of operation.
So the call went out for a machine that would be fast enough to allow for quick movement but small and light enough to be carried by an individual fighter and worn like a backpack. Every prominent manufacturer answered the call, but only the maritime megacorporation Hydrophonics Incorporated brought its financial might and technological prowess to bear on the project.
Development[]
The company immediately set to developing a smaller, faster, more hydrodynamic means of personal underater propulsion. The first prototypes mimicked cephalopods, shaped like oblong ovals and using directional water jets as a means of propulsion and a magneto-hydrodynamic engine for power. The idea behind magneto-hydrodynamics was as practical as it gets: Utilizing a gold-sealed cyinder of copper coils and containing a series of extremely powerful electromagnets fed by extremely efficient lithium-hydrogen cells, the ions in the seawater would be attracted and repulsed by the magnetic forces and effectively pull the water through the jet ducts, providing approximately 4,800 pound of thrust and rocketing the PUPS at 12 knots (13 mph or 6 meters per second). Except for the shape, these ultimately proved unsuccessful because the mechanism to control the jets' vector was unreliable. The magneto-hydrodynamic engine was prone to unexpected surges of power that produced too much pressure for the jets to handle, rupturing the lines and dislodging the nozzles. This made the machine uncontrollable and dangerous to operate, sometimes blasting the user with high-pressure streams strong enough to tear wetsuits and abrade skin. After months of trying to iron out the problems with little success, the magneto-hydrogynamic system was dropped entirely for the proven sealed lithium-ion battery of centuries past.