Then Death and Hades were thrown into the lake of fire. This is the second death, the lake of fire; and if any one's name was not found written in the book of life, he was thrown into the lake of fire.
Revelation 20:14-15
Let me give you a little bit of metaphysics: Hell is a place where the Logos no longer exists. Meaning is grasped for, but cannot be found, because the provider of meaning, of Truth, has disappeared. One is attracted to their own nameless fears, but there is no longer a person inside you who can grasp who they are. Yet you suffer, and you suffer tremendously, and the spiritual suffering--mostly caused by the absence of any meaning--is impossible to overcome because it's impossible to even think enough to formulate a plan to overcome it. One is stuck forever in a loop of physical and spiritual torment, and there is nothing that can be done to escape it. That is Hell.