Underwater Cities
Underwater Cities explained: play cards to action slots, match colors for extra effects, build connected cities and manage production across three eras.
Develop a network of underwater cities, tunnels and production facilities while pairing cards with action spaces on a shared board.
Matching a card’s color to the chosen action lets you resolve both the board action and the card, creating the game’s central efficiency puzzle.
Why We Love It
Every turn asks whether the action space or the card effect matters more. The best turns align both, while weak turns often sacrifice one side to preserve tempo.
About Underwater Cities
Players construct domes, farms, laboratories, desalination plants and tunnels on personal networks.
Three production phases convert that infrastructure into resources and points, rewarding engines that come online at the right time.
Game at a Glance
Play a Card
Pair one card with an available action space.
Build Cities
Expand domes and connect them through tunnels.
Produce
Three production phases reward developed networks.
Score the Network
Endgame points reward cities, facilities and special cards.
Who Underwater Cities suits
Players who like long-form engine building, card synergy and worker-placement-style competition for action spaces.
Rules overview
On each turn, play a card and place your action marker on an available action slot. If the card color matches the slot, resolve both effects; otherwise only the action applies. Actions build tunnels, cities and facilities, gain resources, improve income and acquire cards. Production occurs three times during the game, and final scoring evaluates the completed underwater network.
Key decisions
Editorial analysis: A strong card is not automatically a strong play. Value comes from matching it to an action that advances the same plan, especially before production when infrastructure has time to repay its cost.
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Learn Underwater Cities in depth
Sources and edition notes
Facts checked September 17, 2026. This guide covers the base game.