His secret place; or, his hiding-place; i.e. he covered himself with dark clouds, from hence he secretly shot at his enemies, as it follows. Dark waters, i.e. watery vapours and thick clouds, as the next words expound these.
Related Commentaries of Psalms 18:11
Psalms 18:11
11 He made darkness his secret place; his pavilion round about him were dark waters and thick clouds of the skies.