Hades' Cave

Hades' Cave is a cave deep underground where the god Hades lives in. It is deep enough underground that there are cracks in parts of the cave that allow some, all be it a little bit of magic to pass through. The cave can be reached by going along a series of tunnels buried under the basement of Dragon Hall. The Cave appears in Descendants 3.

Creation
During his time on the island, he tried to blast his way through the barrier, as well as paying a number of pirates to build a ladder so he could reach the top where he believed the barrier would be weak. Finally, Hades had a number of demons, pirates, and goblins try to dig a tunnel so that he could go under the dome. Unfortunately, he and the demons got hopelessly lost. Giving up, Hades summoned his biggest and strongest demons and had them clean up the largest part of the tunnel which he would turn into his cave.

Hades
Hades is the only confirmed permanent resident of the cave. While Hades, like so many others who live on the Isle of the Lost are bitter and miserable, Hades has attempted to make the best of a horrible situation. He created his cave by breaking down part of the tunnel which he likely did to make his cave resemble his kingdom of the Underworld. While he is in the cave, he enjoys playing rock and roll albums loudly on an old record player while air-guitaring, he enjoys playing an actual guitar (loudly). He possesses a broken television implying that at one time he enjoyed watching TV. Hades also has minions that he sends on errands such as getting his coffee.

Possible Residents
Pain and Panic - In Escape from the Isle of the Lost: A Descendants Novel, it is mentioned that Pain and Panic (Hades' most loyal minions) were also exiled to the Isle of the Lost. When Hades ruled the Underworld they lived in it, so it is likely that they lived underground with their master and thus it is possible that they dwelt in his cave. There is however no confirmation on where they live.

Hadie - Hadie is mentioned in Return to the Isle of the Lost: A Descendants Novel. It is mentioned that he is the son of Hades and has his father's blue hair. Nowhere does it mention who Hadie's mother is. Since the book has no mention of his mother, it is quite possible that Hadie lives with his father. If that is the case, Hadie would be a resident in Hades Cave. This however cannot be confirmed.