John Calvin Commentary Psalms 69:1

"Save me, O God; For the waters are come in unto my soul." — Psalms 69:1 (ASV)

Save me, O God! for the waters, etc. Under the figure of waters, the Psalmist represents his condition as so extremely distressing that it brought him even to the brink of despair. Yet we know that, far from being a soft person or one lacking in fortitude, he was someone who encountered and overcame dreadful temptations with extraordinary courage. From this, we may infer the bitterness of the distress with which he was afflicted at that time.

Some understand the word soul as denoting life; but this gives a very cold and unsatisfactory meaning. It rather signifies the heart.

When a man falls into an abyss of waters, he may for some time prevent the water from entering his body by stopping his mouth and nostrils. But eventually, because it is impossible for a human being to live without respiration, suffocation will compel him to let in the waters, and they will penetrate even to the heart.

By this metaphor, David would suggest not only that the waters had covered and overwhelmed him, but also that he had been forced to draw them into his body.