Waters turning red:


Revelation 8:8,9 (NIV):
The second angel sounded his trumpet, and something like a huge mountain, all ablaze, was thrown into the sea. A third of the sea turned into blood, a third of the living creatures in the sea died, and a third of the ships were destroyed.


Revelation 11:6 (NIV):
They have power to shut up the heavens so that it will not rain during the time they are prophesying; and they have power to turn the waters into blood and to strike the earth with every kind of plague as often as they want.


Revelation 16:3,4 (NIV):
The second angel poured out his bowl on the sea, and it turned into blood like that of a dead person, and every living thing in the sea died.
The third angel poured out his bowl on the rivers and springs of water, and they became blood.