Heresy of the Hidden Temple
As the name suggests, the planet is largely covered in oceans dotted with small volcanic islands and inhospitable rocks jutting from the water. Its fisheries and aquaculture are a major source of for the Askellon sector. Its shipyards produce some of the sector's best watercraft, including designs dating from before the Great Crusade, which has given the Adeptus Mechanicus a vested interest in the planet's manufacturing history. Its civilized denizens are a maritime people uncomfortable being far from the coast, with many living most of their lives aboard gigantic city-ships and most never leaving sight of the open water for long. Pisceran nobles measure their wealth and prestige in the of their fleet and splendor of their flagships, and many serve in the Imperial Navy and the Imperial Guard. Piscerans of all classes tend to enjoy drink, gambling, and have a great respect for martial deeds. Chartist ships stop at Piscera on the way to or from Port Aquila.
Hive Nammu sprawls across the planet's largest island, Kur-Enki, which lies to the northwest of the mainland. The wealthiest citizens of Hive Nammu live inside massive spires along the shore, where they can enjoy the beauty of the oceans without suffering the noises, smells, and dangers it can present. Poorer citizens live farther down the hive, with the least fortunate making their homes near the piers, often falling victim to tidal waves or attacks by carnivorous wolf-crabs. The population density dwindles as one travels towards the center of the island, which is dominated by shipping warehouses and the planet's only spaceport, Port Weyland.
There is only one proper continent on the planet, consisting of a barren rocky desert known as the Sealess Shore to the west, misty, towering mountains in the center, and peninsulas at either end, covered in dense jungle and populated by primitive human tribes that live in the mainland's savannahs and along the edges of the jungles. Civilized people consider the landmass cursed, and even the tribals avoid the deepest jungle and the mountainous highlands. The tribes of the northwestern peninsula are the most civilized and the only ones who interact meaningfully with who they call the "Sea People". They are largely insular, but outsiders have been able to earn their trust and even become adopted into the tribe. They export hides, furs, bushmeat, and occasionally produce relics from the deep jungle. Most other mainlander tribes either flee from technological people or attempt to fight them.