From The Diary itself.
"I, Sister Faustina Kowalska, by the        order of God, have visited the Abysses of Hell so that I might tell souls        about it and testify to its existence...the devils were full of hatred for        me, but they had to obey me at the command of God, What I have written is        but a pale shadow of the things I saw. But I noticed one thing: That most        of the souls there are those who disbelieved that there is a hell." (Diary        741)
                                                 
           The Apostle of Divine            Mercy
          St. Maria Faustina Kowalska
          of the
          Congregation of the Sisters of Our Lady of Mercy
                      
          "Today, I was led by an angel to the Chasms of Hell. It is a place of            great torture; how awesomely large and extensive it is! The kinds of            tortures I saw:
          The First Torture that constitutes hell is:
     The loss of God.
          The Second is:
     Perpetual remorse of conscience.
          The Third is
     That one's condition will never change.
          The Fourth is:
     The fire that will penetrate the soul without            destroying it. A terrible suffering since it is a purely spiritual            fire, lit by God's anger.
          The Fifth Torture is:
     Continual darkness and a terrible suffocating smell,            and despite the darkness, the devils and the souls of the damned see            each other and all the evil, both of others and their own.
          The Sixth Torture is:
          The constant company of Satan.
          The Seventh Torture is:
          Horrible despair, hatred of God, vile words, curses and blasphemies.                                                   These are the Tortures suffered by all the damned together, but that            is not the end of the sufferings.
          
           Indescribable Sufferings
          There are special Tortures            destined for particular souls. These are the torments of the senses.            Each soul undergoes terrible and indescribable sufferings related to            the manner in which it has sinned.
           
          I would have died
          There are caverns and pits            of torture where one form of agony differs from another. I would have            died at the very sight of these tortures if the omnipotence            of God had not supported me.
           
          No One Can Say There is No Hell
          Let the sinner know that he will be tortured            throughout all eternity, in those senses which he made use of to sin.           I am writing this at the command of God, so that no soul may find            an excuse by saying there is no hell, or that nobody has ever been            there, and so no one can say what it is like...how terribly souls            suffer there! Consequently, I pray even more fervently for the            conversion of sinners. I incessantly plead God's mercy upon them. O My            Jesus, I would rather be in agony until the end of the world, amidst            the greatest sufferings, than offend you by the least sin." (Diary            741)