And the angels which kept not their first estate, but left their own habitation, he hath reserved in everlasting[AIDIOS] chains under darkness unto the judgment of the great day.
When did this happen? We're not really told anything much about this, it's just referenced briefly.
6And the angels who did not stay within their own position of authority, but left their proper dwelling, he has kept in eternal[AIDIOS] chains under gloomy darkness until the judgment of the great day—
Another reference--Peter knew about this event
4For if God did not spare angels when they sinned, but cast them into hell[TARTURUS] and committed them to chains of gloomy darkness to be kept until the judgment;
--2 Peter 2:4
Tarturus is defined by e-sword as the deepest abyss of hades.
2And the earth was without form, and void; and darkness was upon the face of the deep.
[the face] "of the deep"
(Usually feminine) from H1949; an abyss (as a surging mass of water), especially the deep (the main sea or the subterranean water supply): - deep (place), depth.
And we see this same happening in Revelation to Satan
1And I saw an angel come down from heaven, having the key of the bottomless pit[ABYSS] and a great chain in his hand.
2And he seized the dragon, that ancient serpent, who is the devil and Satan, and bound him for a thousand years,
The angels left their own habitation and did what?
Is it related to this passage?
4The Nephilim were on the earth in those days, and also afterward, when the sons of God came in to the daughters of man and they bore children to them. These were the mighty men who were of old, the men of renown.
The Nephilim would have been wiped out by the flood, but we see the problem might continue after the flood. The same word--nephilim-- is used in post-flood passages.
And there we saw the giants, the sons of Anak, which come of the giants: and we were in our own sight as grasshoppers, and so we were in their sight.
From H5307; properly, a feller, that is, a bully or tyrant: - giant.
A primitive root; to fall, in a great variety of applications (intransitively or causatively, literally or figuratively): - be accepted, cast (down, self, [lots], out), cease, die, divide (by lot), (let) fail, (cause to, let, make, ready to) fall (away, down, -en, -ing), fell (-ing), fugitive, have [inheritamce], inferior, be judged [by mistake for H6419], lay (along), (cause to) lie down, light (down), be (X hast) lost, lying, overthrow, overwhelm, perish, present (-ed, -ing), (make to) rot, slay, smite out, X surely, throw down.
Does Jesus reference this same problem when he talks about how it will be in the last days [of the age]?
For as in the days that were before the flood they were eating and drinking, marrying and giving in marriage, until the day that Noe entered into the ark,
If God covered the earth with water in the flood, wiping out all living, couldn't he have done it before [gap]? If he is creating a new heaven and new earth in Revelation, couldn't he have done that before?
5And he that sat upon the throne said, Behold, I make all things new.
Of uncertain affinity; new (especially in freshness; while G3501 is properly so with respect to age): - new.
I'm going to take a look at the book of Enoch which apparently is still canon in the eastern church.