Then I saw an angel coming down from heaven, holding in his hand the key of the bottomless pit and a great chain. (Rev 20:1)
Rev 20:1 is a text used by proponents of a flat earth being a biblical doctrine (yes, such a movement still persists even today, sadly). Writing in response to this, Robert Sungenis wrote the following (note: Sungenis refers to the book of Revelation as the Apocalypse [a designation I prefer, too]):
The mere fact that the RSV puts "bottomless" and "pit" in the same sentence tells us immediately that the translators understood the phrase symbolically, since a "pit," in colloquial parlance, is not bottomless. The phrase "bottomless pit" is a common, although somewhat graphic, translation of the Greek αβυσσος, more commonly understood as "abyss." It appears nine times in the New Testament, but seven of them are in the Apocalypse of John (Lk 8:31; Rm 10:7; Ap 9:1, 2, 11; 11:7; 17:8; 20:1-2). The other two passages refer only to something that is deep. Luke 8:31, for example, use αβυσσος in reference to a lake into which the demon-possessed pigs were cast by Jesus. Romans 10:7 uses αβυσσος in reference to the place in which bodies are buried. Hence these two passages throw a dim light on translating αβυσσος as "bottomless pit," much less will it allow a flat-earther to use this symbolic passage to teach the Earth is flat. This is why most English translations render αβυσσος as "abyss," while the KJV and RSV are the only popular translations that render it "bottomless pit." The reason the majority of Bibles simply translate αβυσσος to "abyss" is that the exact meaning of the word is ambiguous. In general, it refers to a demote and unseen location that disallows movement and activity (e.g., as in Ap 20:1 in which Satan is chained so that he cannot move about; or as in Rm 10:17 in which a place of burial is one in which the dead are inactive). In the end, it does not refer to a "bottomless pit," per se, and thus there is no recourse for the flat-earther to claim that the Apostle John is contradicting a globe earth. (Robert A. Sungenis, Flat Earth/Flat Wrong: An Historical, Biblical and Scientific Analysis [State Line, Pa.: Catholic Apologetics International Publishing, Inc., 2018], 170-71)