Caerule

Caerule is an isolated ocean world located in the Segmentum Obscurus. This watery world is the current Adeptus Astartes homeworld of the Argent Blades Space Marine Chapter. It is from here, that the Chapter stands eternal vigil over their demesne, guarding themselves against the ever-present threat of Chaos incursion from the Eye of Terror.

Background
The homeworld of the Argent Leviathans is Caerule, a medium sized ocean world where 95% of the planet's surface is covered by a single Great Ocean known as the Abyssi Magnae. All of the planets cities reside on the small amount of land, because of this the planet has a fairly small population of 6 Billion. However the only source of food comes from the Abyssi Magnae but more dangerous game also live within. The Great Ocean is home to the Chapter's namesake - Leviathans, a species that has been known to come in various shapes and sizes, from the dangerous yet killable Banshee Leviathan to the great Revenant Leviathan of legend. The planet is distantly governed yet fiercely protected by the brothers of the Argent Leviathans.

Kar'Morgh
Kar'Morgh is the Capital city of Caerule, located in the Southern Hemisphere of the planet. Kar'Morgh is a by far the largest city on Caerule, however, in comparison to other Imperial hive cities it is actually relatively small only having a population of 4 billion.

Fortress-Monastery
The Argent Leviathans Fortress-Monastery is located roughly 5 kilometres off the coast of the planets Capital City. The Fortress Monastery, Aqua Domumus, is located entirely under the Great Ocean, in a small underwater cave in order to provide more environmental protection. Aqua Domumus is lined with thousands of weapon emplacements, including Heavy Bolter emplacements, Plasma Cannon Emplacements and most weapons that are able to be used while underwater.