The Basin in the Cave

• Type: Magical Receptacle; Horcrux Defense
• Owners: Lord Voldemort (creator)
• Maker: Lord Voldemort

The Basin is a large, stone receptacle located in the center of a crystalline island within a seaside cave. Described as being as wide as a cauldron, the basin is carved from stone and appears to rise seamlessly from the island's surface. It is filled to the brim with a mysterious, emerald-green liquid that glows with a “phosphorescent light.” This liquid is the Potion of Despair, a powerful Dark potion that induces pain, terrifying visions, and extreme thirst in the drinker. Lying at the bottom of the basin, visible through the potion, is the object it is meant to protect—in this case, one of Lord Voldemort's Horcruxes, the locket.

The Basin is the central component of a complex and cruel magical defense system. Its properties are intrinsically linked to the potion it contains. The primary function of the basin is to ensure that an intruder can only access the Horcrux within by drinking the entire volume of the Potion of Despair. The enchantments placed upon the basin and its contents are formidable:

• The potion cannot be vanished, parted, scooped, siphoned, or transfigured.
• It cannot be charmed or otherwise magically removed from the basin.
• Albus Dumbledore deduced that the basin would magically refill itself with the potion if its contents were emptied by any means other than being drunk.

The sole method to lower the level of the potion is for a wizard to drink it, thereby subjecting themselves to the potion's horrific effects and rendering them extremely vulnerable. This act serves as a testament to Lord Voldemort's belief that his enemies would be too weak or too compassionate to force another to endure such an ordeal.

The Basin was created by Lord Voldemort sometime after he created his locket Horcrux. He chose a remote sea cave he had visited as a child and established it as the hiding place for this piece of his soul. To test the defenses, he brought his house-elf, Kreacher, to the cave and forced him to drink the potion from the basin. Though left to die by Voldemort, Kreacher was able to escape using house-elf magic. Later, a disillusioned Regulus Arcturus Black learned of Voldemort's Horcrux and resolved to destroy it. Accompanied by Kreacher, he returned to the cave. It was Regulus who drank the potion from the basin this time, enduring the torment so that he could switch the real locket with a fake one. He then ordered Kreacher to take the true Horcrux and destroy it before being dragged to his death by the Inferi in the surrounding lake. In 1997, Albus Dumbledore and Harry Potter journeyed to the cave in their hunt for Horcruxes. Recognizing the nature of the enchantment, Dumbledore drank the entire potion himself, suffering immensely but allowing Harry to retrieve the locket from the now-empty basin. This act severely weakened the Hogwarts Headmaster just before their return to the Astronomy Tower.

The Basin is a pivotal object in Harry Potter and the Half-Blood Prince. It represents the pinnacle of Lord Voldemort's cruel ingenuity and his mastery of the Dark Arts. The challenge it presents is not one of magical power, but of endurance and emotional fortitude, forcing an intruder into a state of complete physical and mental collapse. The ordeal at the basin is the direct cause of Albus Dumbledore's severely weakened state prior to his death. His willingness to sacrifice his own well-being to retrieve the Horcrux serves as a final, profound lesson for Harry Potter on the nature of love, sacrifice, and the fight against evil. The scene forces Harry into a position of responsibility, as he must care for his incapacitated mentor and fend off the attacking Inferi, marking a significant step in his journey toward defeating Voldemort.

• In the film adaptation of Harry Potter and the Half-Blood Prince, the basin is depicted as being made of crystal rather than stone, matching the crystalline appearance of the island it rests on (film).