The cave is located within a towering cliff by the sea, and is accessed through a small fissure in the rock face.

From the Story

Harry Potter and the Half-Blood Prince

Discovered in chapter 26, The Cave

Professor Dumbledore and Harry travel to the cave on their search for one of Voldemort's Horcruxes.

The cave is formed of an ante-chamber and an inner chamber. When Dumbledore points his wand at the wall of the cave, an arched outline appears, blazing white as through there is a powerful light behind it. To access the chamber, a blood payment must be made, to weaken any enemy of Lord Voldemort's who tries to enter.

Within the cave is a vast black lake in a cavern so high the ceiling is out of sight. In the middle of the lake is a small island, which is accessed by boat, on which stands a stone basin. The basin is full of a phosphorescent emerald liquid, which is protected by an invisible barrier, unable to be penetrated by a human hand.

Inferi live in the lake, and protect the cave from intruders, attacking when enemies of Lord Voldemort disturb them.