Bottomless pit is mentioned 7 times in the book of Revelation.
It mentions key of the bottomless pit twice.
[Rev 9:1 KJV] 1 And the fifth angel sounded, and I saw a star fall from heaven unto the earth: and to him was given the key of the bottomless pit. [Rev 20:1 KJV] 1 And I saw an angel come down from heaven, having the key of the bottomless pit and a great chain in his hand.Abaddon (Apollyon) is the angel of the bottomless pit.
[Rev 9:11 KJV] 11 And they had a king over them, [which is] the angel of the bottomless pit, whose name in the Hebrew tongue [is] Abaddon, but in the Greek tongue hath [his] name Apollyon.The beast came out of the bottomless pit.
[Rev 11:7 KJV] 7 And when they shall have finished their testimony, the beast that ascendeth out of the bottomless pit shall make war against them, and shall overcome them, and kill them. [Rev 17:8 KJV] 8 The beast that thou sawest was, and is not; and shall ascend out of the bottomless pit, and go into perdition: and they that dwell on the earth shall wonder, whose names were not written in the book of life from the foundation of the world, when they behold the beast that was, and is not, and yet is.The devil is cast into the bottomless pit.
[Rev 20:2-3 KJV] 2 And he laid hold on the dragon, that old serpent, which is the Devil, and Satan, and bound him a thousand years, 3 And cast him into the bottomless pit, and shut him up, and set a seal upon him, that he should deceive the nations no more, till the thousand years should be fulfilled: and after that he must be loosed a little season.The Greek word used for the bottomless pit is “abyssos”.
https://www.blueletterbible.org/lang/le … =G12&t=KJV
“Abyssos” is also translated “deep”.
[Luk 8:31 KJV] 31 And they besought him that he would not command them to go out into the deep. [Rom 10:7 KJV] 7 Or, Who shall descend into the deep? (that is, to bring up Christ again from the dead.)https://debatingchristianity.com/forum/viewtopic.php?p=970403#p970403