The lake of fire may be a real place or a metaphor as scripture gives no literal location, but is very descriptive as a place of outer darkness and torment and being eternal as all those people including Satan, the beast and the false prophet that are cast into it will be remembered no more.
The duration of punishment for the one cast into the lake of fire is everlasting. Isaiah speaks of the everlasting burning of the fire that shall never be quenched and of the worm which shall never die (Isaiah 33:14; 66:24). David said that some would awake unto eternal life and others unto shame and everlasting contempt (Daniel 12:2). John the Baptist and Jesus spoke of the unquenchable fire (Matthew 3:12; Mark 9:43). Paul the Apostle speaks of how the lost will be punished with everlasting destruction from the presence of the Lord (II Thessalonians 1:9).
The Apostle John says that the smoke of their torment ascendeth up for ever and ever; and they shall have no rest day and night; and they shall be tormented day and night for ever and ever (Revelation 14:11; 19:3; 20:10). Jesus said that the lake of fire is a furnace of fire in Matthew 13:41, 42 and outer darkness in Matthew 22:13.
The fact that the lake of fire is eternal is plain from the following verses where it is described as:
1. Everlasting fire.......................Matthew 25:41
2. Everlasting punishment...........Matthew 25:46
3. Eternal damnation..................Mark 3:29
4. Everlasting destruction.......... II Thessalonians 1:9
5. Everlasting contempt..............Daniel 12:2
6. Torment forever and ever.......Revelation 14:9-11
7. Blackness of darkness forever.....Jude 1:13
8. Vengeance of eternal life............Jude 1:7
9. Lake of fire--forever and ever......Revelation 20:10
10. Second death--forever..............Revelation 20:14
11. Elements melt, earth and works are burned up.......2Peter Chapter 3
God gives us a description as in fire and brimstone which can be used literal as in Sodom and Gomorrah burned to ashes and as a metaphor for torment, suffering, punishment or as Matthew 8:12 describes it as outer darkness. The New Testament description is a bottomless pit (abyss) (Revelation 20:3), a lake (Revelation 20:14), darkness (Matthew 25:30), death (Revelation 2:11), destruction (2 Thessalonians 1:9), everlasting torment (Revelation 20:10), a place of wailing and gnashing of teeth (Matthew 25:30), and a place of gradated punishment (Matthew 11:20-24; Luke 12:47-48; Revelation 20:12-13), everlasting fire Matthew 25:41, everlasting punishment, Matthew 25:46, lake of fire burning with brimstone.
Jude 1:7 clearly states an example of eternal fire. This is the same Greek word that is used for everlasting fire and everlasting punishment as used in Matthew 18:8 and Matthew 25:41,46 (Notice: The place, as no real name is given, where the unsaved go is everlasting punishment, and not everlasting punishing. The punishment is eternal in its results, not in its duration. Unquenchable fire is a fire that cannot be quenched or put out until everything in its path is burned up.
In my own minds eye I see the lake of fire as a place where those who have rejected God, whether they be good or bad people, burning in a torment (fire and brimstone could be a metaphor for torment) of having to see those who have heard the call of God and have accepted Him and now live in a place of paradise with all the fullness of God in all His glory. No more tears, no more hurts, pain sickness, etc, etc. Those in the lake of fire are outside the realm of God continuing in all their sin, sickness, hurts, pain tears, etc. etc., but can see those who are in the glory of the Lord like looking through a window and wanting what others have, but will never have it and this is their torment for eternity as they are constantly consumed with the fire that burns in their souls for what they have rejected and now to late to receive.