The fact that water turns into blood here strongly reminds us of the first plague of the Exodus (Ex. 7:19-21). Turning the Nile into blood would destroy Egypt's economy and comforts in an instance. The lifeblood of Egypt was and is the water of the Nile.
If you have ever traveled to Egypt, you know that it is a lush and productive country along the banks of the Nile, but just a few miles away from the river you will encounter some of the driest, most barren land you will see anywhere. It rains so seldom that the soil is as fine as flour and dusty in the extreme. You can hardly find a blade of weed, much less healthy crops there. In fact, the humidity is so low 10 miles from the Nile that it all but sucks the moisture right out of you. Every time I have had a chance to visit the Egyptian desert, I have had to drink a couple liters on my return or face a serious headache!
Our text contains a second clear allusion--one to God's judgment on ancient Babylon. " 'I am against you, O destroying mountain, you who destroy the whole earth,' declares the Lord. 'I will stretch out my hand against you, roll you off the cliffs, and make you a burned-out mountain' " (Jer. 51:25, NIV). In Jeremiah 51 God pronounced judgment on Babylon because it has oppressed the people of God. So the second trumpet blends elements of the Old Testament judgments on both Egypt and Babylon. What is interesting is that both countries were and are flat, dry, and dependent on the great rivers that pass through them.
But if ancient Babylon was located in a flat river valley, why does this verse speak of a mountain? It is a symbolic reference. Daniel 2 depicts God's kingdom in terms of a great mountain. So Jeremiah's description suggests Babylon is a great counterfeit of God's true kingdom. This trumpet promises that God will destroy that counterfeit in the waters of its own "sea."
The symbolic judgments represented in the second trumpet may well reflect the collapse of the Roman Empire, an event still future at the time that John wrote the book of Revelation. From the point of view of the first readers the empire may have seemed invincible. But the vision assures the prophet that God marks the activities of oppressors on this earth, and He acts at the proper time.
Lord, give me the confidence that matters are still under Your control. May I not grow impatient at the pace of Your interventions.