In the Co-Existed City model, the coastline becomes a hinge—linking what remains in The Terrestrial City with what must be reimagined on water. The result is a Land–Sea Hybrid Civilization: a single urban organism with two zones, designed to stay seamlessly connected as sea levels rise and the shoreline redraws the map.
This framework is built around a clear ratio: 70% remaining territory (the Old Zone / The Terrestrial City) and 30% floating city (the New Zone / Sim Eternal City). The point isn’t separation—it’s continuity. The terrestrial and maritime realms become two working faces of one metropolis, connected through infrastructure, economy, everyday life, and memory.
The co-existed city model map
1) Integrated Transportation and Infrastructure
The first connection is physical: movement, access, and flow.
The Old Zone—The Terrestrial City—retains familiar infrastructure: subways, transit hubs, and logistics corridors. The New Zone—Sim Eternal City—doesn’t replace those systems; it plugs into them.
Subway-to-sea transfers turn mainland stations into coastal gateways.
Electric/hybrid ferries and autonomous shuttles operate like surface subways—high frequency, low friction.
Floating bridges stitch together key maritime sectors, so the New Zone behaves like a neighborhood grid, not an isolated platform.
Now add the personal mobility layer—the “last mile” that makes the Co-Existed City feel like one city:
UAM (Urban Air Mobility) creates weather-aware aerial corridors between rooftop/harbor vertiports and floating platforms.
Drone taxis / eVTOL taxis act as a personal vehicle for cross-zone travel—on-demand, dynamically routed, integrated with city identity and transit systems.
Amphibious autonomous pods support “door-to-dock” movement—vehicles that can transition between terrestrial lanes and floating docks to reduce transfers.
Micro-mobility on water (compact electric watercraft and shared marine mobility) covers short-range travel inside the New Zone.
For goods and resilience, the system expands in parallel:
Drone logistics moves time-sensitive packages and medical supplies across zones.
Autonomous cargo ferries maintain continuous bulk movement.
Submersibles support underwater maintenance, retrieval, and secure transport routes when surface conditions are disrupted.
In other words: the sea doesn’t become a barrier. It becomes another layer of the transit map—with UAM and drone taxis operating as personal-vehicle bridges between The Terrestrial City and Sim Eternal City.
2) Socio-Economic Symbiosis
The second connection is economic: two zones, two logics, one interdependent system.
The Co-Existed City runs on “Selective Fruitful Coexistence”—not as a slogan, but as a governance design.
The Terrestrial City = Selective Capitalism: the Old Zone remains optimized for global finance, premium tourism, high-value business, and concentrated cultural capital.
The Sim Eternal City = Selective Communism: Sim Eternal City becomes an alternative living system—communal assets, technological self-sufficiency, and low-cost daily life.
But neither zone is complete alone. The connection is maintained through exchange:
Sim Eternal City supplies essentials scaled by maritime tech—purified water, bio-fuels, and resilient production.
The Terrestrial City supplies what remains scarce and specialized—financial instruments, global trade networks, high-value arts, and institutional infrastructure.
The shoreline becomes a marketplace—where each side supplies what the other cannot produce as efficiently.
3) Living and Commuting Rhythms
The third connection is social: how people live across both worlds.
The Co-Existed City introduces Mobile Residential Rights—citizenship that isn’t fixed to one territory. People can belong to both zones without being trapped in either.
This creates a new daily rhythm:
Work and public life can remain anchored in The Terrestrial City—offices, studios, institutions, skyscrapers.
Home life can shift to Sim Eternal City—floating neighborhoods designed around affordability, shared systems, and self-sufficiency.
Here, UAM and drone taxis aren’t luxury gadgets—they’re what makes the rhythm practical:
For quick cross-zone commutes, on-demand aerial taxis become the “personal car” substitute in a city where terrestrial land is scarce.
For late-night returns, emergencies, or high-frequency travel, aerial + maritime + autonomous routes provide redundancy so mobility doesn’t collapse when one mode is slow.
So the “commute” isn’t just movement—it’s an identity loop:
The Terrestrial City by day, Sim Eternal City by night—not as migration, but as routine.
Hyundai Motor showcased three mobility solutions for the future - Urban Air Mobility (UAM), Purpose Built Vehicle (PBV), and Hub
4) Historical and Narrative Continuity
The fourth connection is civilizational: memory.
As sea levels rise, the danger isn’t only territorial loss—it’s cultural amnesia.
The Co-Existed City keeps continuity by turning threatened or submerged legacy into living infrastructure:
Vulnerable districts (like parts of Lower Manhattan) remain present through Digital Twins, allowing the city to be navigated, studied, and remembered.
Underwater museums (where submersion has occurred) preserve the physical aura of what was lost—transforming submerged space into a civic archive, not a dead zone.
Sim Eternal City becomes a territory of dignity—a designed continuation of urban identity for displaced citizens.
The result is a city that refuses a clean break. It doesn’t erase the past to build the future—it carries the past forward.
The Sea as a System, Not a Threat
In the Co-Existed City model, the sea stops being an enemy and becomes a platform: modular, adaptive, and deeply connected to The Terrestrial City.
Technology enables the physical link.
Exchange sustains the economic link.
Mobility rights shape the human link.
Digital heritage protects the narrative link.
UAM + drone taxis provide the personal mobility bridge, making terrestrial–maritime life feel seamless.
New York survives not by retreating from water, but by building a civilization that can live with it—on it—without disconnecting from itself.