Price$369.50 – $1208.94
Buy on TCGplayerUnderground Sea
Land — Island Swamp
LegalReserved ListRank #300
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Why is this card good?
Underground Sea is the gold standard of Dimir mana. As a true dual land with both Island and Swamp types, it taps for U or B untapped, enters untapped, and—crucially—is fetchable by any "Island" or "Swamp" fetch land (Polluted Delta, Verdant Catacombs, etc.). That fetchability is the whole point: it makes your mana base more consistent and thins your deck.
Who wants it: Any deck running blue-black, especially competitive and high-power builds where every untapped, on-color source matters. Control, reanimator, and combo decks that need precise mana on early turns benefit most. If you're playing fetch lands, you essentially need duals to make them work.
When to skip it: Budget tables—this is a Reserved List card costing hundreds of dollars, and shock lands, ABU duals' substitutes, or even tapped duals do 90% of the job in casual pods. Don't bother if your deck is three+ colors and you're not running fetches, or if you rarely need turn-one untapped color.
The premium is pure consistency, not raw power.
Related cards
Watery Grave
Shock land producing U/B with basic land types for fetching.
Drowned Catacomb
Untapped dual U/B if you control Island or Swamp.
Polluted Delta
Fetch land that grabs Island or Swamp types like Underground Sea.
River of Tears
Dimir dual adding U/B based on play patterns.
Darkslick Shores
Untapped early-game U/B fast land.
Sunken Ruins
Filter land producing U/B from colored mana.
Dimir Aqueduct
Bounce land taps for both U and B.
Underground River
Pain land giving untapped U or B.
Printings (11)
Rulings (2)
- 2008-10-01
This has the mana abilities associated with both of its basic land types.
- 2008-10-01
This has basic land types, but it isn't a basic land. Things that affect basic lands don't affect it. Things that affect basic land types do.