By awesome deeds you answer us with righteousness, O God of our salvation, the hope of all the ends of the earth and of the farthest seas; the one who by his strength established the mountains, being girded with might; who stills the roaring of the seas, the roaring of their waves, the tumult of the peoples, so that those who dwell at the ends of the earth are in awe at your signs. You make the going out of the morning and the evening to shout for joy.
Psalm 65: 5-8, ESV
King David often referenced creation as comparative evidence of the majesty and greatness of God. As in the portion of Psalm 65 above God's "awesome deeds" are exemplified in his strength to establish mountains and still the roaring seas and waves. These reflections are always theocentric, fine-tuned to the character and nature of the God who spoke the wonders of creation into existence by his Word. There's a side-bar in most of the Psalms, however. David encouraged the readers of his songs to trust this God and discover hope in that relationship. Surely the God who created the mountains and the seas and commands their movement can care for his people and create in them the hope spoken into "ends of the earth and farthest seas".
The mountains and seas of Israel, and several adjoining lands, are most likely King David's reference points. There's little evidence that he would have known the great Pacific and Atlantic oceans or any body of water beyond the Red Sea, the Great Sea (Mediterranean), the Salt Sea (Red), or the Kinneret Sea (Galilee). Even though he mentioned "the farthest seas", his knowledge would have been local. Even more, what he knew about the sea was limited by what was observable or what had been passed to him through ancient oral tradition. There may have also been some fable in his portrayal of monsters and beasts in the deep.
And, that's the point. King David was a man after God's own heart (1 Samuel 13:14 and Acts 13:22). He wasn't perfect by any means. Being allowed to see even small portions of God's creation was enough for him to trust God and know the living hope of that relationship.
Harriet and I are at the beach. I'm sitting on the deck of our first floor condo, hanging over the Atlantic. It's the change of scenery we both needed. The ocean screams his trustworthiness to us, and the hope of the nations. The hand that created this majestic body of water and reigns sovereign over her waves and currents is the faithful One I can trust in matters great and small. That trust calms the waters of my own soul and produces wave after wave of grace and hope. The confidence I always need involves moving my human doubts and fears and anxieties to the edges of life, and trusting him completely. He is my hope.