The Second Trumpet - The Sea becomes blood.
Then the second angel sounded: And something like a great mountain burning with fire was thrown into the sea, and a third of the sea became blood.
And a third of the living creatures in the sea died, and a third of the ships were destroyed. 8:8-9
This sounds much like a volcano whose ash and lava end up in the sea. First, we need to notice the term, the sea. This is not any sea, not all seas, but the Mediterranean Sea; often throughout the Bible, the term, the sea, refers to the Mediterranean Sea. If verse 8 is specifically for that area, so probably also is the devastation of verse 7, for it does not say anything about the whole earth.
In this destruction, thirty-three percent of the creatures of the Mediterranean Sea are destroyed, as are also thirty-three percent of its ships. Here, it might be well to remind ourselves, that to Jewish writers of two thousand years ago, numbers frequently represented unspecified amounts.
Some teachers suggest that this description refers to the eruption of Mt. Vesuvius, in AD 79; even though Mt. Vesuvius erupted before John wrote The Revelation. If Mt. Vesuvius is being referred to here, John was writing history, not prophecy.
If one wants to update this prophecy could one see that this refers to modern warfare on the Mediterranean Sea.
Then the second angel poured out his bowl on the sea, and it became blood as of a dead man; and every living creature in the sea died.16:3
The striking similarity between the second trumpet and the second bowl of wrath is that both affected the sea so that the waters of The Mediterranean Sea became blood and caused death in the sea.
There is also a notable difference; in 8:9 John says, a third of the living creatures in the sea died, but here in 16:3 the writer says that every living creature in the sea died.