[IN WHICH THE NORTH ATLANTIC IS A SCARY PLACE]
Type-4b "Iceberg Princess"
Discovered by accident by CSG-8, the Iceberg Princess is an almost complete unknown, compared to the Northern Ocean Princess. Orbital and high-altitude reconnaissance has tentatively located her base of operations in the area of Nuuk, Greenland. All communications with the city have ceased, and the city itself is under a 1600 feet thick layer of ice and cannot be seen.
Unlike "Mittens", all that is known to us about the Iceberg Princess comes from long-range photography, mostly by high-endurance drones. It is not much.
We know that her personal (permanent) fleet is composed of two Heavy Cruisers, an indeterminate number of Light Cruisers and Submarines, three Escort Fortresses and two subordinate Airfields.
The Princess herself, however, does not appear to have any guns or planes under her direct control. Instead, she relies entirely on her control over the icebergs that break off the glacier she has created.
These "Abyssal 'Bergs", as they have been called, are visually identical to normal icebergs, but can travel enormous distances, all while remaining under her control. They have been spotted as far south as the Equator.
It's the capabilities of these icebergs that makes them, along with the submarines, the reason for the extinction of the Atlantic Trade. They can move on their own, even against the current, can submerge completely and will employ several complex tactics to hunt ships. At night, these icebergs can only be spotted by radar. Submerged, they are transparent to sonar. Rumors of versions that employ Abyssal ECM/ECCM cannot be confirmed.
And, although they are usually seen working in groups, even a lone iceberg can snare as big a ship as an aircraft carrier, as CSG-8 discovered, to their cost. All task forces operating in Atlantic waters must mantain constant aerial and radar surveillance, especially at night, and all unknown contacts must be engaged with extreme prejudice.
Should collision occur, no attempt at saving the vessel must be made. In the case of steel vessels, survivors on lifeboats must navigate to a safe distance from the ship before a rescue can be attempted.
Once an iceberg has made contact with a ship, it will begin to "spread". Eventually, it will cover the bottom of the vessel, at which point the ice will lift the ship out of the water and carry it north, towards the Iceberg Princess. The ice will then continue to spread, focusing on potential egress points of the victim vessel. It will even attempt to protect the vessel from scuttling fire.
Transmissions from CSG-8 showed that these attacks are accompanied by visual and audio anomalies. In these, a small, albino girl in a white dress with black accents, with hair arranged in pigtails will plead an beg the crew not to resist. She will offer protection, safety, and promise that she "will not let anyone sink, ever again". As the ice spreads, more anomalies will manifest, taking the vague shape of children. Crewmembers reported hearing the voices of lost relatives or loved ones, begging them to stop fighting. In one case, the deceased had died without the sailor's knowing.
How these icebergs can move cannot be determined at this moment. Their method of detecting ships is also unknown; examples have been observed changing course to intercept from as far as 300 nautical miles away.
Samples taken have not shown to be anything other than sea ice.
The Iceberg Princess's base contains a sizable fleet of captured vessels. These include several cargo and passenger vessels, two submarines, and the entirety of CSG-8. The ships are almost completely sealed with ice, and are regularly visited by Abyssals and the Princess herself. The status of the crews and passengers remains unknown.
(In which the Abyss start to become the horrors from the deep they're supposed to be.)