If you say that a place or a situation is hell on earth or a hell on earth, you are emphasizing that it is extremely unpleasant or that it causes great suffering.
[emphasis]
She believed she would die in the snake-infested sand dunes. She said: 'It was hellon earth'.
See full dictionary entry for hell
hell on earth
a place or a situation that is extremely unpleasant or that causes great suffering
Organizing it all has been hell on earth, but it's worked absolutely brilliantly.