Revelation 16:1-16

Vs1-2: The first bowl of God's wrath will cause ugly open sores on those with the mark of the beast, worse than any hives or flesh-eating bacteria we have ever seen. It will not affect those who worship the Lord God.
Vs3: The second bowl of wrath comes in quick succession. It makes the Mediterranean Sea water red like blood and kills everything in the sea, maybe like that red algae that kills everything? Remember, Revelations pertains to Israel and the Mideast region. This is all literal, just like it says. Don't spiritualize it. The context will tell you when to spiritualize it.
Vs4-6: This judgment against the creation of God is now going against all water sources of the world, not just the Mideast.
Vs7: The angels are saying God is fair, with all the bad things happening on the earth at this time of Revelation.
Vs8-9: The sun gets too hot and burns men. Instead of asking God for forgiveness, these men just blasphemy God more. They were unrepentant. Vs10-11: THE 5TH JUDGEMENT IS darkness and tongue pain. It is little known, but in the 1700's, there was an area in North America that went black for 3 days. Even candles and lights didn't give much light. At the end of the 3 days, the people there were starting to go insane. These people learned in 3 days how awful complete darkness actually is.
Vs12: Now the River Euphrates is the border of the God's people, Israel. This is actually the northern boundary of Israel.