The Seven Last Plagues are sent by God from heaven, angels pour out vials of His wraith upon the face of the earth, and they are laid out..
Grievous sores
Fresh water sources become like blood
Oceans also become like blood
The sun scorching men with great heat
A great darkness
The Euphrates River drying up and unclean spirits
And a destructive earthquake.
The ten plagues that took place in Egypt in the Old Testament are mirrored in the plagues of Revelation. However, the latter is spiritually discerned. In Moses' day, he dealt with Pharaoh in the nation of Egypt. In contrast, the Book of Revelation describes God's Church, the great city that represented Christ during the New Testament. Sadly, this Church has become spiritually known as Egypt (and Sodom). This is where the plagues take place, as they are the judgment of the unfaithful Church, not the world, prior to the Second Coming.
Based on the spiritual condition of the church all over the world, I believe the plagues are already taking place if you understand what that spiritually means. There will NOT going to be a literal blood in the ocean, the Sun burn men, literal locusts eating crops and sting men, total darkness in the land, etc. Its not what you think until you are given spiritual eyes and ears to know what God is doing with His unfaithful church.
Selah.