Hundun's Hideaway is the final main area of the game, at the end of the Sunken City. Here, the player can battle Hundun and either beat the game the hard way or use his eye to gain entry into the Cosmic Ocean.
Hundun's Hideaway begins just like the three previous Sunken City levels, with normal level generation.
However, no special landmarks spawn here, such as the Sun Challenge, Altars, or even Goliath Frog chunks, and instead Hundun will be ascending up to the player using an ascending pit of spikes, destroying every block and item in its way.
Whether the player defeated Hundun or not, the spike pit will inevitably drive them to a massive arena at the top of the level, where they are forced to finish the fight if they haven't yet. If Hundun is defeated, both its eye and the door to complete the game the hard way will open. Shooting the eye of Hundun with the Arrow Of Light, fired using Hou Yi's Bow, will open the portal to the Cosmic Ocean.
- Hundun and the spikes driving the player upward can be incredibly intimidating, especially if they are carrying Hou Yi's Bow and the Arrow Of Light. Despite this, Spelunkers should still take caution avoiding Frogs, Regenerating Blocks, and especially Arrow Traps, as being poisoned by one at this point will mean it is impossible to cure without having to die.
- Some players prefer using more open chunks in the beginning stages of the level to defeat Hundun as it ascends, as there is a window where only the ostrich head is out of its eggshell, allowing one to "nip it in the bud", so to speak. This can be difficult, as the player will generally be confined to tight spaces and have to take their time to progress upward, meaning one should have a plan to ascend after completing their task.
- Arrow Traps, Sticky Traps and enemies can still spawn in the arena, meaning if the player reaches it early, they should dispatch of these hazards as soon as possible so not to disturb them during the battle with Hundun.