**Subsurface oceanic habitats** ---- **Subsurface oceanic habitats (SOHs)** are specially designed and maintained human settlements that exist beneath the icy crust of worlds such as [[wiki:danavus|Danavus.]] They are engineered to withstand immense external pressures and the frigid temperatures of the subsurface oceans, constructed from strong and lightweight materials such as titanium alloys and carbon fiber composites. These materials are often sourced from [[wiki:plateia|Plateia,]] but can also be extracted from mining operations on asteroids or the other moons of Perkunos. The architecture of these habitats are intrinsically modular by intent, consisting of interconnected domes and cylinders that can be either affixed to the ice-crust, be suspended in the water at a desired depth through changes in buoyancy within affixed floaters, or placed at the rocky bottom of the global ocean. These modular designs allow for easy expansion, reconfiguration, and even mobility of the structures. The inner surfaces of these modules are fabricated with thermal insulating materials to protect against the cold of the ocean and retain generated heat. Although the ocean of Danavus is dozens of times deeper than those found on Plateia, differences in the world's gravity allow the pressure at the bottom to be comparable to the deepest parts of Plateia's own oceans, making habitation at the bottom feasible with current technology. The life support systems of the SOHs are primarily dependent on nuclear or geothermal energy, which can harness the heat from the moon's core as ejected through geothermal vents on the ocean floor for both heating and electricity. Compact nuclear reactors are an otherwise common power source, especially for colonies not in vicinity of geothermal vents. Water is sourced directly from the subsurface ocean and purified through a series of advanced filtration and sterilization processes. Oxygen, rather than being imported, is generated via electrolysis of water and through the cultivation of algae and other aquatic plants in hydroponic gardens. These gardens also contribute to food production, supplemented by heated aquaculture systems that farm species of fish imported from Plateia. Transportation within the SOHs is facilitated by pressurized tunnels and trams that connect different modules of the settlement. For external exploration and transport, specialized submersibles are used, capable of withstanding high pressures and navigating the challenging terrain of the ocean floor. Autonomous drones are also deployed for exploration and sample collection, navigating through ice crevices and vent systems. The original focus of these settlements were scientific research, particularly in the fields of astrobiology, exogeology, and oceanography. However, as human colonization continued over time with competing colonial powers, these settlements are also seeing increased armament and security. {{tag>techs-civilian offworld_colonization}}