The coastline has always represented a boundary in Civilization 6—a hard stop for settlers and a frontier for naval power. Land is for settlement, and the sea is for movement and resources. But what if this fundamental rule were broken? Imagine a game where any coastal water tile is a valid spot for a new city. This single change wouldn’t just be a minor tweak; it would trigger a seismic shift, fundamentally rewriting the strategic DNA of the entire game. Analysis on community forums and among strategy experts suggests this would create a more dynamic, complex, and naval-centric world. This guide explores the profound strategic implications of building full cities on the coast, transforming the sea from a barrier into the ultimate prize.
The New Age of Exploration: Early Game Settlement Strategy
The opening turns of Civilization 6 are a frantic race for territory. With the ability to settle on water, this race would explode in a new dimension. The decision of where to plant your first few cities would become dramatically more complex.
Redefining the “God-Tier” Start
According to the player community, a top-tier starting location would no longer be defined solely by clustered land resources, mountains for defense, and freshwater access. Instead, the ideal start would be a “hybrid” location with access to both land and sea tiles for settlement.
- Resource Diversity: A capital on the coast could immediately found a second city one tile into the ocean. This allows the empire to work high-production land tiles (like woods, stone, or deer) and high-food/high-gold sea resources (like fish, crabs, and whales) from the very beginning.
- Strategic Placement: An early water city acts as a forward naval base. It secures vital sea lanes, claims lucrative fishing grounds, and can establish a powerful defensive perimeter against naval incursions long before an enemy could dream of launching an armada.
- Era Score Implications: Being the first to found a city on a new continent is a source of Era Score. With water settlement, being the first to found a “pelagic city” (a city not touching any land) could become a new, highly contested source of early Era Score, pushing players into daring oceanic expansion.
Many professional gamers suggest that the classic strategy of a tight, defensible core of land cities would be challenged by a more expansive, archipelago-style empire. A player might settle two cities on their home continent and then immediately leapfrog a settler across a narrow sea to claim a strategic island or resource-rich reef, a move that is currently impossible in the early game.
Reimagining Global Trade: The Economic Revolution
The ability to build cities directly on coast tiles would completely overhaul the global economy, making naval trade the undisputed king of commerce.
The Rise of the Thalassocracy
A thalassocracy is a state that uses its naval power to dominate trade. With underwater cities, every coastal civilization would have the potential to become one.
- Trade Route Dominance: Trade Routes would become almost exclusively sea-based. They would be longer, connecting far-flung ocean cities, and therefore significantly more profitable. A single Trader in a water city could generate immense wealth, but this also makes them prime targets.
- The New Commercial Hub: The Harbor district would become the most important economic district in the game for any coastal empire. For underwater cities, it would be their very essence. Player discussions theorize the emergence of new district types, such as a “Marine Commerce Hub” that combines the functions of a Commercial Hub and a Harbor, or an “Aquaculture Dome” that acts as a super-powered Granary.
- Resource Monopolies: Strategic resources on the sea floor, particularly Oil, would become the focal point of mid-to-late game conflict. A civilization that secures the majority of the world’s offshore oil reserves through a network of water cities would have a stranglehold on modern military production. Analysis on forums shows that players believe new underwater luxury resources would be necessary, such as Pearls, Coral, or even “Bioluminescent Algae,” to make ocean territories more valuable.
Policy cards like Maritime Industries (faster production for naval units) and Triangular Trade (more gold from trade routes) would shift from situational picks to essential components of any winning strategy.
The Blue Battlefield: Warfare and Naval Dominance
If cities can exist on water, then land armies lose their status as the primary tool of conquest. The battleship, not the tank, would become the ultimate arbiter of power.
The Irrelevance of the Land Army
In a world dotted with ocean cities, a massive land army becomes a regional police force, not an instrument of global domination.
- Siege Warfare, Reimagined: How do you siege a city that’s completely underwater? Analysis suggests that the Submarine would be re-classed as a naval siege unit, capable of exerting zone of control and directly attacking city centers from beneath the waves. Melee naval units like the Ironclad would function like naval battering rams.
- The Power of the Blockade: A popular strategy would be the complete naval blockade. By surrounding an enemy’s ocean city with a fleet, you could cut it off from all trade and effectively starve it into submission without firing a shot. This makes a powerful, well-rounded navy—with fast ships for blockading and strong ships for fighting—absolutely critical.
- Choke Points and Strategic Canals: A one-tile-wide channel of water between two landmasses would become the most valuable strategic terrain in the game. A city built in that channel, supported by a fleet, could control the movement of all ships between two oceans, effectively cutting the world in half.
The Aircraft Carrier would see its role elevated to the pinnacle of power projection. A Carrier battle group could appear off the coast of any continent, establish air superiority, and systematically dismantle coastal and ocean cities with impunity. Land-based fighters would be unable to respond effectively over vast ocean distances.
A Cultural Abyss: The Impact on Culture and Tourism
The shift to an aquatic world would also have profound, if less obvious, effects on the pursuit of a Culture Victory.
- New Wonders, New Aesthetics: The community imagines a host of new wonders. The city of Atlantis could be a World Wonder that must be built on a coast tile and provides immense culture and tourism. The “Mariana Trench Research Lab” could be a late-game scientific wonder that provides a massive boost to science and reveals the entire map. Existing wonders like the Colossus and Great Lighthouse would become even more vital.
- Underwater National Parks: The concept of a National Park would need to be expanded. A stunning Coral Reef with high appeal could be designated as a Marine Sanctuary, generating huge amounts of tourism, especially if adjacent to an underwater city with a “Sea-Floor Resort” building.
- The Great Works of the Deep: Great Artists, Writers, and Musicians would find new inspiration. We would see Great Works of Art titled “Bioluminescence,” novels about deep-sea exploration, and symphonies that capture the crushing pressure and serene beauty of the ocean depths.
A Culture Victory would require a civilization to not only be a patron of the arts on land but also a steward of the ocean’s beauty, creating a global tourism network that spans both land and sea.
Charting the Depths: The New Tech and Civic Tree
Such a fundamental change would necessitate a significant overhaul of the Technology and Civic trees. The current trees are overwhelmingly focused on land-based development.
- Early Game Divergence: A popular theory is that the Sailing technology would be joined by a new “Submersible Construction” tech, allowing for the creation of the first underwater Settlers. This would be a major strategic choice in the Ancient Era.
- A Maritime Civic Branch: A new branch in the Civic tree would be required, focusing on maritime law and governance. Civics like “Code of the Sea” could unlock powerful naval policies, while “Oceanic Governance” could allow for the construction of unique underwater city improvements.
- Late-Game Frontiers: The Future Era would be dominated by oceanic concepts. Technologies like “Seasteading” could unlock floating districts, “Geothermal Power” could be harnessed from undersea vents, and “Advanced Aquaculture” could solve food shortages globally.
These changes would make the path of scientific and cultural progress less linear, forcing players to decide whether they want to invest in mastering the land or pioneering the ocean.
The New World Order: Winners and Losers of the Aquatic Age
Not all civilizations are created equal, and the shift to an aquatic world would dramatically shake up the tier lists.
S-Tier: The New Masters of the Ocean
- Norway (Harald Hardrada): Already a naval powerhouse, Norway would become terrifying. The ability to perform coastal raids would now mean they can pillage districts in ocean cities directly. Their Longships would allow them to establish early dominance over the seas and their economy.
- England (Victoria): The Royal Navy Dockyard is already one of the best unique districts. In a world where every city can be a port, its ability to produce ships faster and grant a free naval unit on other continents would be game-breaking. England could build an unstoppable armada with shocking speed.
- Japan (Hojo Tokimune): Japan’s Meiji Restoration ability, which grants adjacency bonuses for clustered districts, would be incredibly powerful for tightly packed ocean cities. Their Electronics Factories would supercharge the production of a modern navy.
- Indonesia (Gitarja): The ability to buy naval units with Faith and the unique Kampung improvement, which can be built on coast tiles, would make Indonesia an immediate top-tier contender. They could settle tiny, otherwise useless islands and turn them into powerhouse cities.
The Losers: The Landlocked and Left Behind
- Scythia (Tomyris): An entire civilization built around land-based cavalry would find itself contained to its home continent, unable to project power globally.
- Inca (Pachacuti): The Inca’s mastery of the mountains would become a footnote. Their Terrace Farms and mountain tunnels are useless in a world dominated by naval conflict.
- Mali (Mansa Musa): While still an economic force, Mali’s focus on desert cities and land trade routes would put them at a severe disadvantage compared to civilizations that can generate massive wealth from sea trade.
Systemic Shock: Necessary Mechanic and UI Overhauls
For this concept to be playable, several core game systems would need a complete redesign.
- UI and Visuals: The game would need a new visual “layer” to allow players to see and manage the districts and improvements of underwater cities without the surface of the water obscuring them.
- District Adjacency: Adjacency bonuses would be re-written. An underwater Campus might get a bonus from Geothermal Vents. An Industrial Zone might get a bonus from being next to a cluster of sea-floor mining operations.
- Loyalty and Grievances: Loyalty pressure would likely need to be reduced over water, making it easier to maintain the loyalty of far-flung ocean colonies. Declaring war to “liberate” a captured ocean city would likely generate fewer grievances than conquering a historic land-based capital.
- New Natural Disasters: Hurricanes would become even more threatening. New disasters like Tsunamis, which could damage coastal and ocean cities, or underwater volcanic eruptions that could destroy districts, would add new environmental challenges.
In conclusion, allowing cities to be built on coast tiles would be the single most impactful change imaginable for Civilization 6. It would transform the game from a land-based struggle with naval support into a true “blue marble” simulation where control of the oceans is the key to victory. The strategic depth would be immense, forcing players to rethink every aspect of expansion, economy, warfare, and culture. The familiar rhythm of the game would be replaced by a new, dynamic, and unpredictable contest, not for who rules the land, but for who commands the planet’s vast and unforgiving oceans.