GAT-X255 Forbidden Blue

The Forbidden Blue is a Mobile Suit Variation from the series Gundam SEED.

Combat Abilities
The weaponry of the Forbidden Blue was designed after the one used on the original GAT-X252 Forbidden, but the individual weapons were mostly replaced by ones better suited for underwater combat. The weaponry includes a phonon maser cannon, torpedo launchers, CIWS guns and machine guns for ranged combat, while spikes and a trident are used for close combat.

Ranged Combat
For ranged combat the suit is equipped with a single phonon maser cannon, mounted on the backpack but only usable in close-combat mode. This weapon is the only energy weapons installed on the suit. Also used for ranged combat are two supercavitating torpedo canister pods used to fire torpedos. These pods are mounted on the arms connecting the shields with the backpack.

Close Combat
For close combat the suit features four retractable close combat spikes, with two spikes mounted in each shield. Another weapon used in close combat is a single trident which serves as an optional hand armament.

Shell-firing weapons
The Forbidden Blue is equipped with a total of four shell firing weapons. These include two head mounted "Igelstellung" 75mm multi-barrel CIWS guns and two "Armfeuer" 115mm machine guns, mounted on the forearms of the suit. These guns are also the only weapons retained from the original Forbidden.

Geschmeidig Panzer
As with the other suits derived from the original GAT-X252 Forbidden, the main special feature of the suit is its "Geschmeidig Panzer" energy deflection armor, which is mounted on the two shields of the suit. This system is used to move through water and counteract water pressure. However, the system proves to be a flawed design, as it is reliant on its "Geschmeidig Panzer" system to protect against water pressure. This means that if the battery fails in deep water, the Forbidden Blue will be rapidly crushed, earning it the unflattering nickname "Forbidden Coffin". This design flaw is later correct in the GAT-706S Deep Forbidden and the GAT-707E Forbidden Vortex, with both suits featuring an additional reinforced titanium armor around the cockpit, granting the pilots survival if the Geschmeidig Panzer failed.

Tail extension
The Forbidden Blue is equipped with a tail extension, which mounts an ultra-long-wave antenna, a towed sonar array and an anchor. The first two equipments grant the suit advanced sensor capabilities if used underwater.

Sensors
Besides the one mounted on the tail extension, the Forbidden Blue is equipped with a large number of different sensor systems, granting it superior sensor capabilities compared to other suits. These sensors include IR sensors, a sonar, lorenzini sensors and several ultra-low-light cameras.

Besides all these features the suit is also equipped with the new Trans-Phase armor, similar to the one used on the original Forbidden.

History
After ZAFT stole four Gundam-type mobile suits created as part of the G Project by the Earth Alliance, the EA created a new set of Gundams, this time made up of only three units. One of these suits was the Forbidden, piloted by "Biological CPU" Shani Andras. The design of the Forbidden was eventually converted into a new series of underwater-use mobile suits to counter ZAFT's own underwater models. The first of these new models was the Forbidden Blue, which greatly resembled the Forbidden and also used many system features and weapons installed on the original unit. These equipments were however partly replaced or expanded to make the suit more efficient underwater. Also the new Forbidden Blue doesn't utilize a Biological CPU like the original Forbidden but instead relies on a standard Natural-use OS.

After production, one Forbidden Blue was tested by underwater ace Jane Houston, who used such a suit in the Second Casablanca Sea Battle on July 24, CE 71, which also marks the formal introduction of the Forbidden Blue in battle. Another unit was covertly transferred by Muruta Azrael to Orb's Rondo Sahaku faction.

Due partly because of its design flaw regarding the Geschmeidig Panzer system, the suit has largely been replaced by the successor units Deep Forbidden and Forbidden Vortex. Especially the later one is better than the Forbidden Blue since it uses the exact same equipment and weaponry, but corrected the fatal design flaw. Visually, both suits are indistinguishable from one another.