Adam Clarke on Psalms 18:4

The sorrows of death compassed me - חבלי מות chebley maveth, the cables or cords of death. He was almost taken in those nets or stratagems by which, if he had been entangled, he would have lost his life. The stratagems to which he refers were those that were intended for his destruction; hence called the cables or cords of death.

The floods of ungodly men - Troops of wicked men were rushing upon him like an irresistible torrent; or like the waves of the sea, one impelling another forward in successive ranks; so that, thinking he must be overwhelmed by them, he was for the moment affrighted; but God turned the torrent aside, and he escaped.