There go the ships - There the vessels move along - objects that would, of course, attract the attention of one looking at the sea, and admiring its wonders. The psalmist is describing the active scenes on the surface of the globe, and, of course, on looking at the ocean, these would be among the objects that would particularly attract his attention.
There is that leviathan - The Septuagint and the Vulgate render this, dragon. On the meaning of the word “leviathan,” see the notes at Job 41:1.
Whom thou hast made - Margin, as in Hebrew, “formed.” The idea of creation is implied in the word.
To play therein - As his native element. To move about therein; to make quick and rapid motions, as if in sport.