It is accessed by defeating Mom's Heart or It Lives! within 30 minutes. Leaving and reentering the Boss Room after the times has reached 30 minutes will make the entrance to the Blue Womb disappear. If the player is fast enough, both Boss Rush and Blue Womb can be completed in a single run.
It contains the following:
- 4 golden chests in the main room. Unlike the ones in The Chest, these are just regular golden chests and don't guarantee an item drop.
- 2 locked Treasure Rooms, both of them offering two choices of items as if More Options was active. Taking one item will cause the other to disappear.
- A shop that always contains 6 items, even if shop upgrade Lvl. 4 has not been unlocked.
- A 2x2 boss room that contains Hush. The door leading to the boss room might be confused by players as part of the northern wall, but will slide away upon approaching it.
!It is advised to enter the Blue Womb only with very powerful items and/or a set of good dodging skills, because Hush ranks amongst the most difficult bosses of the entire game. After Hush is defeated, one of two things will happen:
- If this is the first time Hush has been defeated, a giant golden chest will appear in the middle of the room. Jumping into it ends the run and gives Ending 17.
- If Hush has been defeated before, a trapdoor leading to Sheol and a beam of light leading to the Cathedral will appear instead.
|Normal & Hard Mode|
|The Basement • The Cellar • Burning Basement|
|The Caves • The Catacombs • Flooded Caves|
|The Depths • Necropolis • Dank Depths|
|The Womb • Utero • Scarred Womb|
|Sheol • Cathedral • Blue Womb|
|The Dark Room • The Chest|
|The Basement • The Caves • The Depths • The Womb • Sheol • The Shop • Ultra Greed|