God reveals His judgment through Scripture, speaking of Sheol, Hades, Gehanna, and Tartarus. Then there is the Lake of Fire. And there is the outer darkness. Some of these may be referring to the same thing. Some of them definitely are not referring to the same thing. Sheol, for instance, appears to be the place of the dead before Christ died.

Something happened when Jesus led captivity captive: after He died, He preached in Hell to the dead who were there by the Holy Spirit. So there is a lot of speculation about this in the theological world, but we do know that something happened.

There will be a time when Gehenna will be thrown into the Lake of Fire. It seems that this is Hell being thrown into the Lake of Fire. Hell is referred to by words that really mean age but are most often translated as forever. The Lake of Fire will be to the Ages of the Ages, which is wrongly translated as forever and ever.

Here are some of the things that are said about Hell and the Lake of Fire:

the lake that burns with fire and sulfur
lake of fire
fiery furnace
destroy both soul and body in hell
punishment
their worm does not die and the fire is not quenched
punishment of eternal (reference to an age) destruction
cast them into hell and committed them to chains of gloomy darkness
smoke of their torment
being in torment

You might find this page interesting. It is an interview with a person who went to Hell and came back.

Psalm 49:13–14
This is the path of those who have foolish confidence; yet after them people approve of their boasts. Selah. Like sheep they are appointed for Sheol; death shall be their shepherd, and the upright shall rule over them in the morning. Their form shall be consumed in Sheol, with no place to dwell

Matthew 10:28
And do not fear those who kill the body but cannot kill the soul. But rather fear Him who is able to destroy both soul and body in hell.

Matthew 25:41
"Then He will also say to those on the left hand, 'Depart from Me, you cursed, into the age-lasting fire prepared for the devil and his angels ...'

2 Peter 2:4
For if God did not spare angels when they sinned, but cast them into hell and committed them to chains of gloomy darkness to be kept until the judgment

Isaiah 66:24
"And they will go out and look upon the dead bodies of those who rebelled against me; their worm will not die, nor will their fire be quenched, and they will be loathsome to all mankind."

Mark 9:43
If your hand causes you to sin, cut it off. It's better to enter eternal life with only one hand than to go into the unquenchable fires of hell with two hands.

Jude 7
And don't forget Sodom and Gomorrah and their neighboring towns, which were filled with immorality and every kind of sexual perversion. Those cities were destroyed by fire and serve as a warning of the eternal fire of God's judgment.

"And the smoke of their torment ascends forever and ever (to the ages of the ages); and they have no rest day or night, who worship the beast and his image, and whoever receives the mark of his name."

2 Thessalonians 1:9
They will be punished with eternal (reference to an undetermined amount of time) destruction, forever separated from the Lord and from his glorious power.

Matthew 13:41–42
The Son of Man will send his angels, and they will remove from his Kingdom everything that causes sin and all who do evil. And the angels will throw them into the fiery furnace, where there will be weeping and gnashing of teeth.

Matthew 13:50
... throwing the wicked into the fiery furnace, where there will be weeping and gnashing of teeth.

Revelation 20:15
And anyone whose name was not found recorded in the Book of Life was thrown into the lake of fire.

Matthew 25:41
"Then the King will turn to those on the left and say, 'Away with you, you cursed ones, into the eternal (of the age) fire prepared for the devil and his demons.' "

Revelation 19:20
And the beast was captured, and with him the false prophet who did mighty miracles on behalf of the beast—miracles that deceived all who had accepted the mark of the beast and who worshiped his statue. Both the beast and his false prophet were thrown alive into the fiery lake of burning sulfur.