Seatroopers battling Sedrians on Sedri.
Many of the standard technologies employed by the Imperial military were modified for aquatic use, including specialized aquatic garrisons, custom TIE fighter boats, and powerful AT-AT swimmers. The armor of the seatrooper was based on the lightweight scout trooper design. It was worn over a two-piece environmental body glove that provides protection from uncomfortable temperature extremes, or toxic-water environments. Designed specifically for engagements on Dac and Tibrin, the seatrooper's armor was pressure-sealed to a maximum of ten atmospheres and included a rebreather that allowed to stay underwater for more than a hour. The armor was more flexible than standard stormtrooper designs, preserving and even increasing a trooper's underwater dexterity. Supplementing a soldier's swimming skills are a back-mounted propulsion unit, and a pair of propulsion boots with snap-down flippers. Since blaster ranges are often adversely affected by underwater use, the seatroopers carried a blaster rifle/speargun hybrid as a standard weapon. In 137 ABY, the seatroopers of Darth Krayt's Galactic Empire used plasma rifles.
The standard seatrooper utility belt includes high-tension wire, grappling hooks, spare blaster power packs, ion flares, concentrated rations, spare comlink, medpacs, rebreather filters, and a compressed air inflatable bubble tent.
Seatroopers also used the SG-4 blaster rifle which was capable of firing miniature harpoons underwater.
Seatroopers on Iskalon during the Galactic Civil War
Aquatic assault stormtroopers were the successors of the clone SCUBA troopers that participated in the Clone Wars as part of the Grand Army of the Republic.
A variation was seen on the planet Iskalon some time after 3 ABY. This variation consisted of a regular stormtrooper helmet and upper body armor over heavy white coveralls. The back-mounted propulsion unit also incorporated an air supply, but the propulsion boots did not have flippers. Thousands of aquatic stormtroopers were used by the Empire to conquer Manaan.
Seatroopers, along with representatives from every specialized Stormtrooper Corps, were assigned to Darth Vader's personal Death Squadron. At some point after the Battle of Endor, in large part due to the seatroopers' prowess in aquatic combat, the Rebel Alliance mobilized the Mon Calamari Knights to aid in the liberation of various aquatic worlds, since they were uniquely qualified to deal with the seatroopers.
Alpha Squadron of seatroopers during the Second Imperial Civil War.
During the Second Imperial Civil War Aquatic assault stormtroopers were also employed by the Imperial Army on the planet Dac for the extermination of the Mon Calamari people ordered by Emperor Darth Krayt. Following the overthrow of the One Sith, the seatroopers came under the control of the Galactic Federation Triumvirate, a new galactic government consisting of the Fel Empire, the Galactic Alliance Remnant, and the New Jedi Order. Seatroopers serving under the Imperial Knight Yalta Val took part in the liberation of Mon Calamari and Quarren slaves who had been coerced into building ships for a pirate syndicate led by the rogue Sith Darth Luft. Seatroopers played an important role in apprehending the pirates, who were subsequently handed over to the authorities.
Seatroopers first appeared in the Marvel Comics story Star Wars (1977) 74, which was first released on May 17, 1983. Seatroopers subsequently appeared in several Legends Expanded Universe literature including the Imperial Sourcebook, Death Star Technical Companion, and the Dark Horse Comics series Star Wars: Legacy and Star Wars: Legacy Volume 2.