An aquatic transport was deployed by an assault squad of Mon Calamari from the Mon Cala planetary defense services, commanded by Commander Gial Ackbar, during an attack targeting Imperial Colonel Bergon's aerial landing platform in 18 BBY. This vehicle enabled them to achieve flight, and subsequently submerge underwater as the Empire initiated defensive measures, which allowed the Mon Calamari to approach the landing platform and fire missiles, resulting in the platform's destruction and the death of everyone on board.
The initial appearance of these aquatic vehicles, though without a specific name, occurred in Darth Vader (2017) 15, a canon comic book written by Charles Soule, with illustrations by Giuseppe Camuncoli, and published in 2018.