Sunken Treasure is a Treasure-Odyssey card from Allies. It is a gainer that can gain any Action card from the Supply, with no cost restrictions, as long as you don't already have a copy of the card you want to gain in play.
It is part of a split pile that it shares with the other Odyssey cards: , , and .
 Official FAQ
- If there's no such Action in the Supply, you don't gain one.
 External strategy articles
- Works perfectly with single played self-trashers like e.g. , ...
 English versions
|| Gain an Action card you don't have a copy of in play.
|| March 2022
 Other language versions
|| Versunkener Schatz
|| Nimm eine Aktionskarte, von der du keine gleiche Karte im Spiel hast.
Sunken Treasure can get you stuff you don't have yet.
 Secret History
The third card was initially a with +2 Cards in front of it and "discard 2 cards" after it. An old concept, tried years ago. You know this time it didn't exactly fail, it just didn't want to be in the pile and then there was no home for it. I followed it with a treasure that cared how many types you had in play, then "gain an Action card from a pile that isn't full," then the final card.