The floods have lifted up, O Lord— Instead of waves at the end of the verse, some translators read roar, which is equivalent to voice. The meaning of the verse is, "Multitudes of combined enemies threaten to break in upon us, like a flood."
Related Commentaries of Psalms 93:3
Psalms 93:3
3 The floods have lifted up, O LORD, the floods have lifted up their voice; the floods lift up their waves.