The floods; the enemies of thy kingdom, who are oft compared to floods for their numbers, force, rage, &c. See Isaiah 8:7,8 Isaiah 17:12,13 Jer 46:7,8. They have both by their words and actions made opposition against it.
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.