Psalms 18:3-5

3 I called to Yahveh, who is worthy of praise, and I was delivered from my enemies. 4 The weeds of death were wrapped around me; the torrents of destruction terrified me. 5 The weeds of Sheol entangled me; the snares of death confronted me.

The psalmist pictures a terrifying death of getting pulled down into the sea and trapped there by entangling weeds. If the disaster is not abated, then Sheol (the state of being dead) would be the result. But God comes to the rescue and prevents that terrible death.