Revelation 16:3
Then the second angel emptied his bowl into the sea, and it turned into blood like a dead man's, and every living thing that was in the sea died.
Revelation 8:8-9
Then the second angel blew his trumpet, and what seemed to be a great mountain, all ablaze with fire, hurled itself into the sea, and one-third of the sea was turned into blood,
Revelation 11:6
They have the power to shut up the sky, so that no rain will fall upon the earth as long as they prophesy, and they have power over the waters to turn them into blood, and to smite the earth with any plague as often as they please.
Revelation 10:2
and he had a little book open in his hand. He set his right foot on the sea and his left foot on the land,
Revelation 13:1
Then I stood on the sand of the seashore, and I saw a wild beast coming up out of the sea with ten horns and seven heads, with ten diadems on his horns, and blasphemous titles on his heads.