An underwater variant of the MVR-3 speeder bike, known as the mini-sub, was modified by the cathedral factories of the Xi Char and participated in aquatic combat during the era of the Clone Wars.
A large, singular laser cannon was equipped on the mini-sub, in addition to armored protection for the droid pilot. These craft were deployed to underwater combat zones via dedicated carriers.
Numerous instances of these underwater vehicles being torn apart by the riding beasts utilized by the Mon Calamari Knights were recorded.
As recompense for their inability to replicate the transformation capabilities of the Vulture-class droid starfighter in their manta droid subfighter, the Xi Char furnished the Trade Federation with underwater adaptation kits for the MVR-3 speeder bike.