Old Key

Old Keys are a utility item used mainly to open treasure rooms in the Deep Mine and the Undergrove. Locked doors in these areas consume one Old Key each, so they are best treated as a limited resource when exploring underground or searching for loot.

They can be obtained from several different activities. Old Keys may be found by breaking Old Barrels or Wheelie Bins, by digging up buried treasure while Metal Detecting, and as random chest rewards in the Undergrove and Island Reef. They can also be produced or traded for through other systems: Crab Pots can yield them depending on the biome they are placed in, the Key-Cycler on Jimmy's Boat exchanges Relics for Old Keys after a short wait, and the Key Cutter can generate one Old Key every 7 days once placed, functioning much like an automated production station.

Because treasure rooms are locked behind Old Keys, it is worth planning ahead before entering the Deep Mine or exploring the Undergrove in earnest. Bringing a supply of keys lets the player open multiple doors without having to backtrack, and it can make long runs much more rewarding if treasure rooms are reached consistently. Since the item has several acquisition methods, players can build a steady stockpile over time instead of relying on a single source.

• Breaking Old Barrels and Wheelie Bins is a straightforward way to find Old Keys while exploring.
• Metal Detecting can uncover buried treasure that includes Old Keys.
• Crab Pot results vary by biome, with rivers being the best option for key-related loot.
• The Key-Cycler on Jimmy's Boat converts Relics into one Old Key after about 10 minutes.
• The Key Cutter is a passive source, producing one Old Key every 7 days after being placed.
• Since locked treasure rooms consume one key per door, carrying extras is useful before entering the Deep Mine or Undergrove.