Luke 21:25
"Then [Note: This event answers to the "immediately" of Matt. 24:29, and suggests the next major event on God's calendar] there will be [supernatural] signs [evident] in the sun and moon and stars. And on earth [there will be] distress among nations; they will be perplexed by the roaring of the ocean's churning waves. [Note: Probably this is figurative language for highly agitated conditions on earth].
Revelation 17:1
Then one of the seven angels, who had the seven bowls, came and spoke to me, saying, "Come [here]; I will show you the punishment [to fall] on the great prostitute who is situated on many bodies of waters.
Revelation 17:15
Then the angel [See verses 1,7] said to me, "The waters you saw, on which the prostitute sits [See verse 1] are races, crowds, nations and language groups.