2 Peter 2:4 refers to Tartarus and not all English translations muddy the water with the mistranslation as "hell."
CEB
God didn’t spare the angels when they sinned but cast them into the lowest level of the underworld and committed them to chains of darkness, keeping them there until the judgment.
CJB
For God did not spare the angels who sinned; on the contrary, he put them in gloomy dungeons lower than Sh’ol to be held for judgment.
CEV
God did not have pity on the angels that sinned. He had them tied up and thrown into the dark pits of hell until the time of judgment.
DARBY
For if God spared not [the] angels who had sinned, but having cast them down to the deepest pit of gloom has delivered them to chains of darkness [to be] kept for judgment;
DLNT
For if God did not spare angels having sinned but handed-
them-over
to chains
of gloom, having cast-
them-into-hell, being reserved for judgment;
DRA
For if God spared not the angels that sinned, but delivered them, drawn down by infernal ropes to the lower hell, unto torments, to be reserved unto judgment:
EHV
For if God did not spare angels when they sinned but handed them over to chains of darkness by casting them into hell, to be kept under guard for judgment;
EXB
[L For if] When angels sinned, God did not ·let them go free without punishment [spare them]. [L But] He sent them to ·hell [L Tartarus; C a Greek term for the underworld] and put them in caves of darkness where they are being held for judgment [Gen. 6:1–4; Jude 6].
HCSB
For if God didn’t spare the angels who sinned but threw them down into Tartarus and delivered them to be kept in chains of darkness until judgment;
JUB
For if God did not forgive the angels that sinned, but cast
them down into the deepest abyss {Gr. Tartarus} and delivered
them into chains of darkness, to be reserved unto judgment;
LEB
For if God did not spare the angels who sinned, but held
them captive in Tartarus with chains of darkness
and handed
them over to be kept for judgment,
NABRE
For if God did not spare the angels when they sinned, but condemned them to the chains of Tartarus and handed them over to be kept for judgment;
NTE
God didn’t spare the angels who sinned, you see, but he threw them into the Pit, into dark caverns, handing them over to be guarded until the time of judgment.
TPT
Now,
don’t forget, God had no pity for the angels when they sinned but threw them into the lowest, darkest dungeon of gloom and locked them in chains, where they are firmly held until the judgment of torment.
WEB
For if God didn’t spare angels when they sinned, but cast them down to Tartarus, and committed them to pits of darkness to be reserved for judgment;
YLT
For if God messengers who sinned did not spare, but with chains of thick gloom, having cast [them] down to Tartarus, did deliver [them] to judgment, having been reserved,