Underwater Cities
147 questions players ask about Underwater Cities. Pick one for the answer. See also the full rulebook.
Updated 2026-11-01.
Setup and components
Turns, cards and the Federation track
- In a two-player game, where do the players start on the Federation track?
- Who plays first next round if nobody moves on the Federation track?
- Do you get a Federation track bonus for spaces you pass over, not just the one where you stop?
- Is the discard pile face up or face down?
- How many rounds and turns are there in a game?
- Do you draw up to three cards at the end of your turn?
- Can you play a card you drew or took earlier in the same turn?
- What if you have no cards at the start of your turn?
Action slots and card timing
- In what order do you resolve the played card and the action slot?
- Can you choose an action slot if you cannot perform all of it, or only can after the card gives you resources?
- Can you use only part of an action slot or card effect, such as building just one of two tunnels?
- Must you upgrade the structure you build on the build-and-upgrade slot?
- Can you spend resources gained during an action on the rest of that same action?
- If your card matches the slot colour, must you use its effect?
- When a slot lets you upgrade up to three structures, can they be different types or the same one twice?
- On a slot that builds 2 farms or 2 laboratories, can you build one of each?
- Can you use the always-available slot more than once in a round?
Action cards and the limit of four
- How do you claim an action card and when can you use it?
- Can you use an action card on the turn you claim it?
- Does the limit of four apply to all claimed cards or only action cards?
- Which action card can you discard when you claim a fifth one?
- Can you use the action card you discard to make room for a fifth one?
- When you discard an available action card, can you also use another action card on the same turn?
- Can you use a slot's ability first, then discard and claim the fifth action card?
- Does an action card's permanent effect still work once the card is tapped?
- With an A action slot, can you tap any action card of any colour and still play a card from hand?
Special cards
- When do you pay the credit cost of a Special card?
- Can credits gained from the action slot pay for the Special card you play with it?
- When you take a 1- or 2-credit Special card, must you take the top card?
- Do Special cards in your hand count toward the hand limit?
- Where do Special cards go when you discard or play them?
- Does a discount on playing Special cards also apply when you use a Special action card?
Building, tunnels and your network
- Must a new city be next to a connected city, or can it be built before its tunnels?
- Where can you build a farm, desalination plant or laboratory?
- How must a tunnel connect, and can it run through empty city sites?
- What counts as connected to your network, and does the starting city count?
- Do you need a city next to a metropolis, or only tunnels, to connect it?
- Does a city on a double-tunnel site need both tunnels to be connected?
Production and feeding
- Does a tunnel produce if it is not adjacent to a city, or only touches a metropolis?
- Do you score a point when you upgrade a tunnel?
- How much do three or four upgraded buildings of one type in the same city produce?
- How do production multipliers (x2, x3) work, and what do they multiply?
- What happens if you cannot feed all your cities with kelp?
- What does a connected symbiotic city produce?
Costs, resources and biomatter
- When a card lets you build or upgrade, do you pay the usual cost or the cost on the card?
- Do surcharges on build sites still apply when a build is free, and can biomatter pay them?
- When can biomatter stand in for kelp or steelplast?
- Are resources shown as a requirement on a card spent?
- If a card lets you pay a resource to gain another, can you do it more than once?
- When a card lets you build on an expansion site and shows a steelplast cost, do you also pay the usual build cost?
Metropolises and Government Contracts
- How many Government Contracts are used, and does it depend on player count?
- Are the buildings granted by Government Contracts free?
- Can you claim more than one Government Contract in a turn, and when exactly?
- If two players qualify for a contract and one forgets to claim it, who gets it?
- Do the cities and buildings needed for a Government Contract have to be connected?
- Do upgraded tunnels count toward the six-tunnel Government Contract?
- Which Special cards count toward the Government Contract that needs three Special cards?
- How do you read a blue metropolis: which reward is instant and which is production?
- Does the tunnel-count brown metropolis score every tunnel or only tunnels next to a city?
Final scoring
Solo game
- How do the blocking tiles work in the solo game?
- What counts as a connected city for the solo goal of seven cities?
- Can you use Government Contracts in the solo game?
- How do the end-game cards that reward having the most of a building type score in solo?
- In solo, do the neutral blocker tiles count as another player for cards that use slots occupied by others?
Specific cards and assistants
- What does the green Biodome promo do, and can it be used in solo?
- With Undersea Server Farm, how many cards do you keep at the start of an era?
- What does Demonstration (card 124) cost, and which action cards can it use?
- How does Black Ops Team work: do copies stack, and when does it trigger?
- Does a x3 tunnel space multiply the bonus of Improved Greenhouse (card 66)?
- What does the production symbol on the Trial Run card mean?
- Do cards that copy production, such as Trial Run or Night Shift, include a production multiplier?
- With Secret Mission (card 193), can you take a slot that another player occupies?
- Does Organic Fusion count as building a symbiotic city, and what limits it?
Underwater Cities: New DiscoveriesExpansion
- Is New Discoveries compatible with every printing of the base game, and can you use its boards in a base game?
- Which New Discoveries variants go with which player boards?
- Can you use the Museum, or the other new content, in the solo game?
- Must the New Discoveries solo game use Quick Start and skip round 1?
- In expansion solo with boards 13-16, is the goal 125 points with or without the seven cities?
- In Quick Start, do the resources on your tile replace the standard starting resources?
- In Quick Start, do the Federation symbols on a starting tile give you track bonuses?
- In what order do you do Quick Start setup, and when can you discard down to three?
Underwater Cities: Data EraExpansion
- Can the Data Disc swap-resources action trade several resources in one go?
- Can the data-disc "build on an expansion site" action be used without a build action?
- When can you take the data-disc option of drawing two extra cards?
- How do you play an additional card with data discs, and how many can you play?
- Does an additional card's effect work if its colour does not match, and does it re-trigger the slot?
- How many cards do you draw at end of turn if you played an additional card?
- Does the red Data Era overlay tile still let you build before upgrading?
- How do blue data cities score during Production?
- Do data centers count for older cards that name farms, laboratories or desalination plants?