History
Tyrrhenia was founded slightly later than the earliest Greek civilizations, during an era when the oceans were already populated by merfolk societies. The city began as a mining expedition authorized by Poseidon, king of the seas.
Poseidon sought to strengthen alliances with surface civilizations that honored his brothers, Zeus and Hades. To facilitate trade, merfolk were encouraged to extract valuable metals and gems from the ocean floor. Mining settlements were established throughout the seas, but the basin that would become Tyrrhenia proved to be among the richest deposits ever discovered.
The earliest settlement was little more than a mining camp. As veins of gold, silver, copper, and other precious minerals were uncovered, the camp expanded rapidly. Merchants, craftsmen, and laborers arrived from other merfolk communities, and over time the settlement evolved into one of the largest underwater cities in the oceans.
The Age of Slavers
The relationship between merfolk and humans became strained during the 12th century BC, when pirates began capturing ocean creatures to sell as exotic curiosities and slaves. Mermaids, fish-men, and Nereids were all targeted, but Nereids were especially valuable because of their ability to survive on land for extended periods.
Some fish-men clans participated in these trades, accepting weapons and treasure from pirates in exchange for captured Nereids. These betrayals created lasting distrust between the merfolk peoples.
In response to the growing slave trade, Poseidon and his armies began actively hunting slave ships. Storms, whirlpools, and sudden shipwrecks became common for vessels suspected of transporting captured merfolk.
Over time, this divine intervention effectively destroyed the large-scale slave trade across the Mediterranean.
Withdrawal from the Surface
Relations between humans and merfolk deteriorated further during the era of the Crusades. Human societies increasingly labeled non-human beings as abominations, and merfolk encountered near the surface were often hunted and killed without mercy.
In response, Tyrrhenia and other merfolk settlements adopted strict isolation policies. Contact with the surface world was drastically reduced, and many cities began hiding themselves entirely from human discovery.
Today, Tyrrhenia maintains a zero-human policy. Any human vessel or submersible that approaches too closely risks never returning to the surface.
Technology
Despite their ancient origins, Tyrrhenians possess a sophisticated blend of traditional craftsmanship and underwater innovation.
Construction
Most buildings in Tyrrhenia are water-filled structures, allowing merfolk to swim freely through homes, plazas, and corridors. Architecture relies heavily on carved stone and seabed rock, using techniques similar to those found in human coastal civilizations.
In rare cases, wealthy families maintain air-filled chambers in upper levels of palaces or mansions. These spaces are extremely rare and considered luxurious, as maintaining air pockets underwater requires considerable effort and resources.
Glass used throughout the city is produced using volcanic materials gathered from the nearby submarine volcano Mount Marsili, where skilled artisans combine lava and sand to create durable underwater glass.
Mining
Mining remains the backbone of Tyrrhenia’s economy.
Traditional tools recovered from shipwrecks—such as pickaxes and shovels—are commonly used alongside tools made from coral and stone. Skilled Nereids sometimes employ water manipulation techniques to fracture rock or sift debris in search of valuable minerals.
Heavy materials are transported using large sea creatures. Trained sea serpents pull cargo carts along the seabed, while powerful giant seahorses serve as draft animals comparable to horses on land.
Lighting
Tyrrhenia is illuminated primarily by bioluminescent algae, which are cultivated and housed in glass streetlamps throughout the city.
Glowing coral is also widely used to illuminate major walkways—known locally as swimways—casting soft blue and green light across the city.
Earlier generations used bioluminescent fish for lighting, but algae proved easier to maintain and far more efficient.
Transportation
Because merfolk are natural swimmers, transportation technology is minimal.
Most citizens simply swim through the city’s open architecture. For longer journeys, giant seahorses serve as mounts, while certain Nereids have developed specialized water-powered vehicles that utilize their ability to manipulate currents.
Cuisine
Tyrrhenian cuisine reflects the abundance of life in the surrounding seas.
Staple foods include:
- shrimp and other shellfish
- a wide variety of fish
- seaweed and kelp
Merfolk practice extensive underwater aquaculture, farming:
- clams
- squid
- octopus
- fish
- seaweed forests
Most marine creatures are considered acceptable food sources, though poisonous species such as lionfish are avoided.
Cooking itself is considered a luxury. Restaurants are often located near geothermal vents or underwater volcanoes, where natural heat can be used to prepare food.
Tyrrhenians also produce a powerful fermented drink derived from toxic algae blooms, which acts as a form of alcohol within merfolk culture.
Districts of Tyrrhenia
Tyrrhenia is built in open water within a deep ocean basin surrounded by underwater mountains. In ancient times these natural barriers provided sufficient protection, but in modern centuries the city has been enclosed beneath a massive stone dome with guarded entrances.
The city is divided into several major districts.
The Mining Ring
Located along the outer portions of the city, the Mining Ring contains the tunnels and excavation chambers where Tyrrhenia’s wealth is extracted from the seabed.
The Nereid Quarter
This district houses diplomats, scholars, and travelers. Because Nereids are the merfolk most capable of interacting with surface societies, many cultural institutions are located here.
The Coral Gardens
Vast underwater farms where kelp forests and shellfish colonies are cultivated to feed the population.
The Temple of Poseidon
The spiritual heart of the city, where merfolk gather to honor the king of the oceans.
The Elder’s Hall
Seat of Tyrrhenia’s governing council. The city’s Elders meet here to oversee trade, law, and defense.
The Pearl Markets
A bustling commercial district where pearls, diamonds, and other mined treasures are bought and sold.
The Shipwreck Ward
A salvage district built around ancient shipwrecks recovered from the sea floor. Many tools, weapons, and artifacts used in the city originate from this area.
The Old Stone City
The oldest section of Tyrrhenia, containing the remains of the original mining camp and the earliest stone dwellings of the settlement.
Defenses of Tyrrhenia
Tyrrhenia is protected by a combination of natural barriers and military forces.
Natural Defenses
The city lies over 12,000 feet beneath the ocean surface, where the immense pressure alone makes human exploration extremely difficult.
Additional protection comes from:
- the surrounding submarine mountain basin
- unstable volcanic terrain near Mount Marsili
Military Forces
Tyrrhenia maintains a standing military force of approximately 500 soldiers. These warriors serve for life but otherwise live normal civilian lives within the city.
Weapons used by Tyrrhenian soldiers include:
- metal swords and tridents
- coral weapons
- sharkskin armor
- sea turtle shell shields
Nereids sometimes employ water manipulation techniques in combat, though few masters of these arts remain in the modern age.
Mermaids and fish-men are particularly skilled at stealth, with some fish-men capable of natural camouflage in the dark waters of the deep sea.
Certain merfolk are also capable of a siren’s call, a hypnotic song that can disorient enemies or lull them into sleep.
Secret Defenses
Tyrrhenia’s location is concealed by natural and magical phenomena, including:
- illusionary currents that confuse navigation
- dense fog banks near the surface
- magnetic anomalies that disrupt instruments
In addition to these defenses, Poseidon’s patrols regularly sweep the surrounding seas, ensuring that hostile vessels or intruders rarely reach the city.
