אַ֭חֲרָיו יָאִ֣יר נָתִ֑יב יַחְשֹׁ֖ב תְּה֣וֹם לְשֵׂיבָֽה׃
הינטער זיך לאָזט ער אַ ליכטיקן שטעג;מע מײנט דער תּהָום איז גרײַזגראָ.
Rashi
He makes a path shine after him When he swims and floats in the sea, he makes the path of the deep shine, for at the time he swims, there is no water because of the speed of his swimming.
Rashi
he considers the deep to be hoary To him, the deep is considered to be weak and feeble.