John Calvin Commentary Psalms 89:9

"Thou rulest the pride of the sea: When the waves thereof arise, thou stillest them." — Psalms 89:9 (ASV)

You govern the pride of the sea. I have already observed that what the prophet has until now spoken generally concerning the power of God, is to be referred to the miracle of the deliverance of the Israelites from Egypt, which he now celebrates in express terms. According to the interpretation of some, God is said to still the impetuous waves of the sea, because he does not allow it to break forth and overflow the whole world by a deluge.

But I would read the 9th and 10th verses together, and would understand the prophet as speaking of the Red Sea, which God divided to make a way for the chosen tribes to pass over. The Psalmist adds immediately after, that all the land of Egypt was overthrown as a wounded man. By these words he magnifies the grace of God, which was displayed in the deliverance of the Church.

He intended, there can be no doubt, to set before his own mind and the minds of others, the paternal love of God, to encourage both himself and others to turn to Him for help, with the greater freedom and eagerness. And in affirming that God had broken in pieces his enemies with his mighty arm, he concludes from the past experience of the Church, that his way of acting will always be similar, whenever in his infinite wisdom he sees it is necessary.