The abandoned base is similar to the one the player is given in the beginning of the game; the base is much larger with multiple layers, a dining room, a garden, and multiple chest rooms. The amount of abandoned bases to be randomly spanwed is usually 3 or 4.
Abandoned bases are flooded and all the leaking walls must be repaired with the hammer. The repair action will cost 2 iron for each wall. When all leaking walls are repaired, the water will slowly drain out, being replaced with air the player can breathe.