Compare Douay-Rheims with King James Version side-by-side to understand the meaning.
Psalm 88 stands uniquely as the darkest song in the Psalter. Attributed to Heman the Ezrahite, it is an unrelenting cry of distress with no turn to praise or resolution at the end. The psalmist cries out day and night, feeling that his life has drawn near to Sheol. He counts himself among those who have no strength, like the slain who lie in the grave, whom God remembers no more. It is a terrifying expression of feeling utterly cut off from the divine memory.
The heavy hand of God is felt in the waves that sweep over him. Heman accuses God of putting him in the depths of the pit and causing his friends to shun him. He asks poignant, rhetorical questions: "Do you work wonders for the dead? Do the departed rise up to praise you?" From his perspective, death is the land of forgetfulness where the praise of God ceases. The psalm ends not with a ray of light, but with the statement: "Darkness is my only friend."
The theological weight of this psalm is immense. It validates the experience of the "dark night of the soul" where faith persists ("O Lord, God of my salvation") even when all evidence of favor is gone. It shows that a believer can feel completely abandoned and yet still be praying. It is a testimony to a faith that does not depend on positive emotional feedback.
Christologically, this is the psalm of Holy Saturday. It captures the experience of Jesus on the cross and in the tomb, where He was "cut off" and the waves of God's wrath swept over Him. He entered the land of forgetfulness and experienced the darkness so that we would never be truly abandoned. Because He went into the "lowest pit," He can hear the prayers of those who feel they are in the dark. He is the answer to the questions the psalmist thought had no answer.