Location from One Piece by Eiichiro Oda
The World Government's maximum-security underwater prison, built beneath the ocean floor. Six levels of escalating torture, each more hellish than the last. Luffy broke in to rescue Ace.
Impel Down is the World Government's answer to pirates too dangerous to execute publicly but too notorious to simply kill. Each level is designed around a different form of suffering, and the deeper you go, the worse the crimes — and the worse the punishment. The warden Magellan controls the facility with his Doku Doku no Mi, making his own body a weapon of mass poisoning. No one had ever broken out until Luffy broke IN, triggering a mass prison break that freed some of the world's most dangerous criminals. Blackbeard used the chaos to recruit Level 6 prisoners into his crew. The breakout remains one of the World Government's greatest humiliations — proof that their systems of control have cracks, and that a rubber boy with enough determination can exploit every one of them.
A fortress descending into the earth beneath the sea — each level deeper, hotter, and more terrible. Level 1: Crimson Hell, a forest of blade-leafed trees. Level 2: Wild Beast Hell, populated by massive predators. Level 3: Starvation Hell, a scorching desert. Level 4: Blazing Hell, a lake of boiling blood and fire. Level 5: Freezing Hell, sub-zero wasteland. Level 5.5: Newkama Land, Ivankov's secret paradise between floors. Level 6: Eternal Hell, where prisoners are erased from history. The architecture is brutalist stone and iron, designed to crush hope.
Also known as: Impel Down, The Great Prison, The Underwater Gaol