Note: All Scripture is quoted from the King James version.
The punishment for sin is not being sent to Hell; the punishment for sin is death.
Genesis 2:17 But of the tree of the knowledge of good and evil, thou shalt not eat of it: for in the day that thou eatest thereof thou shalt surely die.
That having been said there are some Denominations who believe that Jesus did indeed spend those three days in Hell, preaching to those who had died before his crucifixion.
So if the punishment for sin is death, then what is death?
Very often we are told that death is eternal separation from God, and to their credit I also believe that eternal separation from God is a large part of death, but it is not all of what death means.
The Revelation tells us that there are two deaths:
Revelation 1:18 I am he that liveth, and was dead; and, behold, I am alive for evermore, Amen; and have the keys of hell and of death.
Revelation 20:14 And death and hell were cast into the lake of fire. This is the second death.
In the Revelation 1:18 Jesus statement that he has the keys of Hell and Death, tells us that whether we suffer Hell or Death is dependent on him. Or in other words he and he alone is the one who will determine where we will spend our eternity. Part of that eternity can be spent in either of two places.
Those who have rejected salvation will initially be sent to Hell, and later cast into the lake of fire.
Matthew 10:28 And fear not them which kill the body, but are not able to kill the soul: but rather fear him which is able to destroy both soul and body in hell.
This tells me that this is the first death, and that at physical death both body and soul will be sent to Hell to await the Great white throne judgment.
Revelation 20:11 And I saw a great white throne, and him that sat on it, from whose face the earth and the heaven fled away; and there was found no place for them.
But neither Hell or death are eternal as is said in Revelation 20:14.
And death and hell were cast into the lake of fire. This is the second death.
and those who had been in Hell will now be cast into the lake of fire.
Revelation 20:13 And the sea gave up the dead which were in it; and death and hell delivered up the dead which were in them: and they were judged every man according to their works.
Revelation 20:15 And whosoever was not found written in the book of life was cast into the lake of fire.
Since death and Hell were cast into the lake of fire those cast into the lake of fire will not ever escape eternity by dying but will suffer torment for all eternity.
Revelation 20:10 And the devil that deceived them was cast into the lake of fire and brimstone, where the beast and the false prophet are, and shall be tormented day and night for ever and ever.