The Chasm of Challenges is a minigame that can be played by Sora in Kingdom Hearts II and Kingdom Hearts II Final Mix. It is located in the Cave of Wonders at Agrabah. The goal of the minigame is to defeat all the Heartless and descend all platforms within a two minute time limit.
In the first visit to Agrabah, Sora must complete the Chasm of Challenges in order to open the door to the Treasure Room. Supposedly, within the Room would be a treasure that The Peddler would accept in exchange for Jafar's lamp. As a reward for finishing the challenge, the door to the Treasure Room unlocks.
Redo the Cave of Wonders: Chasm of Challenges.
In Chasm of Challenges, the player fights Heartless on disappearing floors. You need to clear all 5 floors within 2 minutes or you have to start over. When you begin, the first floor will disappear and you'll have to fight a group of Icy Cubes to go to the next one. Reaching the other floor, you will have to face more Icy cubes, together with some Fiery Globes. After defeating those, you'll fall on a floor with a Fat Bandit on it. Reaching the penultimate floor, You'll confront once more a Fat Bandit, and another group of Fiery Globes. In the last floor, The only enemies are two Fortunetellers, that shouldn't be a big deal. In general, the Chasm of Challenges isn't a big problem at all, but, it is always good to have a Cure or a Potion when needed.