Revelation 8:8,9

8 And the second angel sounded, and as it were a great mountain burning with fire was cast into the sea: and the third part of the sea became blood;

9 And the third part of the creatures which were in the sea, and had life, died; and the third part of the ships were destroyed.

After the second angel sounds, a very large segment of this comet crashes into the sea. A third of the sea becomes as blood due to the red dust from the explosion of the metallic body. All life in the sea over this portion of the earth will die and all ships on it will be destroyed. This could mean a third of one sea but I think it actually means one third of all the ocean surface on earth since the next judgment is on one third of the land surface on the earth.