Another interpretation of "Your righteousness is like the mighty mountains" (Psalms 36:7): These are the deeds of the righteous. Just as the mountains are visible, so too are the deeds of the righteous visible, as it is said, "They shall fear You as long as the sun endures" (Psalms 72:5). "Your judgments are a great deep" (Psalms 36:7): These are the deeds of the wicked. Just as the deep is darkness, so too are the deeds of the wicked darkness, as it is said, "and their deeds are in the dark" (Isaiah 29:15).
The Righteous as Mountains and the Wicked as the Deep
Midrash Tanchuma Buber, Noach 8:4
ד"א צדקתך כהררי אל. אלו מעשיהם של צדיקים, מה ההרים גלוים, אף מעשיהם של צדיקים גלוים, שנאמר ייראוך עם שמש (תהלים עב ה), משפטיך תהום רבה, אלו מעשיהם של רשעים, מה התהום חשך, אף מעשיהם של רשעים חשך, שנאמר והיה במחשך מעשיהם (ישעיה כט טו).