Tribubble Bongo Sub
A product of the Otoh Gunga Bongamaken Collective
The Gungan Bongo sub has the singular distinction of being, simultaneously, one of the most visually interesting vehicles in the Star Wars galaxy, and one of the most ridiculously impractical. The design is brilliant, and as such the vehicle is fast and maneuverable with maximum efficiency, but it is horrendously vulnerable to ocean-going predator, lacking any kind of defensive shielding or offensive weaponry. But, purely as a means of transport, it suffices quite nicely, and a novice operator can figure out the simple controls in no time.
The sub's skeletal underframe is actually grown organically out of a living, bone-like substance in a process carefully guarded by Gungan artisans, while many of the electronic components are obtained via surreptitious trade with the Naboo people. The Bong's ability to dive and surface is also based on organic principles; like many fish, the sub has air chambers containing a spongy material, into which fluid can be pumped to create ballast for diving, and then purged for surfacing...organic creatures use water for this, but the Gungan Bongo uses an oily lubricant with more consistency of performance.
The Bongo uses force fields in place of plasteel domes; another design flaw in my estimation, since without power, the fields won't work for very long. More than likely this was done in an attempt to eliminate the extra weight of plasteel bubbles, aiding in the vehicle's lightweight design.
Interesting features include a central control pod that can eject as an emergency lifeboat, and side bubbles that can be set up to carry either cargo or passengers, depending on the nature of the trip.