Revelation 16:3

Upon the sea. Under the third plague the “rivers and fountains of waters” are similarly affected (v. 4). The sea is useful primarily as a highway for international commerce and travel. It has been suggested that, by the obstruction of international travel and trade (see chs. 13:13–17; 16:13, 14; 17:3, 12), this plague is designed to demonstrate in a signal way God’s displeasure with respect to Satan’s plan to bind the nations of earth together under his control. Compare Balaam’s experience (Num. 22:21–35). Like the first plague, the second is not universal (see on Rev. 16:2).

Blood. Doubtless in consistency, odor, and color, but not necessarily in composition.

Of a dead man. Nothing more offensive can be imagined than the coagulated blood of a dead man.

Every living soul. Or, “every living thing” RSV. The word for “soul” (psuchē) is used of animal life as well as of human life (see on Matt. 10:28; cf. on Ps. 16:10). In Rev. 8:9 psuchē is translated creatures, obviously referring to marine life. In Gen. 8:1 the Hebrew equivalent (nephesh, “living thing”) is similarly used of animals (cf. Job 12:10).