The Treasure Caverns is a secret hideaway behind Peach's castle. It is filled with valuables, and is home to Trouble-making, but not evil, Shadow Demon Archu. There are loads of crystals, and there is an even richer area behind a wall that is behind two stone bars. The only way to enter the secret room is to take a fragment of one of the rare crystals in there and putting it in a hole in the wall. The room is filled with crystals, and there is a rock bridge above a deep pit, with the bottom being filled with miles of lava, which turns into one of the Cave's valuable treasures when it hardens, changing its color to that treasure in the process. Mario has visited the area numerous times, and uses it as a money cache to pay heavy bills, but only by bribing Archu into letting him take some treasures. Mario once actually fought Archu to get some treasures without bribing, but Archu threw him into the stream in it, and out of the waterfall. Archu loves the water in the cavern, but sleeps in the lava. After he wakes up, he flies back out of the place, and cools down the lava in the water. It changes colors into that of one of the valuables in the place, and Archu adds the stuff to his riches. Toad actually claimed the place, and tried to hide it from Mario, but Archu made Toad leave.