Abyss

Even further below the Ancient Basin lies the Abyss, an ancient area full of Vessel corpses and home of the Void. This is where the Vessels were born and where The Pale King took Void in order to create the Kingsmoulds and Wingmoulds. The shades of dead Vessels, the Siblings, wander along the very bottom.

The entrance to the Abyss was sealed after The Hollow Knight was led out of the Abyss. It is accessible only after acquiring the King's Brand from Kingdom's Edge.

The Siblings and Void Tendrils found here will become passive once Void Heart has been obtained.

Lifeblood Core Room
The Abyss contains a door which requires 15 Lifeblood Masks to open, which is most easily opened with Joni's Blessing in conjunction with other lifeblood sources. When the Knight approaches said door with 15 Lifeblood masks, the 15 orbs next to the door will begin to glow, one by one, until the last one is shining a bright blue hue and the blue vines disappear, leaving behind a glimmer with the same bright colour as the orbs. Inside this room, the Knight will go through a series of platforming challenges before getting to a room with a platform, and, on it, the Lifeblood Core charm. In the background of this room is seen the massive multi-eyed head of the Abyss Creature. After obtaining Lifeblood Core from this room, the Knight will wake up next to the vine door, which now has a grey tone, and the room can no longer be entered, and the Arcane Egg contained inside will not be obtainable if missed.

Birthplace
The birthplace of The Knight. Accessible only with the Kingsoul Charm equipped. Its entrance is located at the bottom of the Abyss on the west side. At the end of the area is an egg which, upon being hit with the Awoken Dream Nail, reveals a scene from the past involving Vessels and the Pale King.

Trivia

 * According to the Kickstarter stretch goals, the Abyss was "a massive new expansion for only the hardiest of adventures" and was going to have "4 new bosses", however, this $85,000 stretch goal was not reached.
 * This area does not have a map, instead being shared with that of Ancient Basin. It also does not appear on the zoomed-out version of the map, but does when zoomed-in.
 * The Abyss ambience is the Main Menu theme distorted and slowed down.

Древний котлован O Abismo