Andrew Hamilton of the University of Colorado Boulder presents an Institute for Advanced Study astrophysics seminar on what actually happens inside a rotating black hole. Using a real-time general relativistic black hole flight simulator he built, he takes viewers past the outer horizon toward the inner horizon, the region he argues is the most violent place in the universe, with energy densities that can exceed those of the Big Bang. The talk works through what general relativity predicts occurs at that inner horizon, where infalling radiation and the black hole's own rotation interact in extreme ways, and what this implies about the fate of anything crossing it. Hamilton grounds the physics in visualizations from the simulator rather than abstract equations alone, aiming to show rather than just describe the interior geometry. It runs just under an hour and is aimed at an audience already comfortable with general relativity and black hole basics.