Albert Barnes Commentary Psalms 77:19

"Thy way was in the sea, And thy paths in the great waters, And thy footsteps were not known." — Psalms 77:19 (ASV)

Thy way is in the sea - Probably the literal meaning here is that God had shown his power and faithfulness in the sea (that is, the Red Sea) in delivering his people; it was there that his true character was seen, as possessing almighty power and as being able to deliver his people.

But this seems also to have suggested another idea - that the ways of God, in his providential dealings, were like walking through the sea, where no permanent track would be made, where the waves would close on the path, and where it would be impossible by any footprints to ascertain the way which he had taken. So it is with his doings and his plans.

There is nothing by which people can determine regarding them. There are no traces by which they can trace the divine designs - as no one can follow a person whose path is through the trackless waters. The subject is beyond human reach, and there should be no rash or harsh judgment of the Almighty.

And thy path in the great waters - The additional idea here may be that the ways or plans of God are vast - like the ocean. Even in shallow waters, when one wades through them, the path closes at once, and the way cannot be traced; but God’s goings are like those of one who moves through the great ocean - over a boundless sea - where no one could hope to follow him.

And thy footsteps are not known - The word rendered “footsteps” properly means the print made by the “heel,” and the print made by the foot. The idea here is that there are no traces regarding many of the dealings of God, which appear most incomprehensible to us, and which trouble us most, as there can be no footprints left in the waters. We should not venture, therefore, to sit in judgment on the doings of God or presume that we can understand them.