The answer is: The second trumpet

Revelation 8:8-9 - The second trumpet brought judgment, with a blazing mountain cast into the sea, turning water to blood.

The image of water turning to blood can be quite striking and foreboding. This event occurs during the Trumpet Judgments, specifically linked to the second trumpet sounding in Revelation 8:8-9. When the description talks about “a great mountain burning with fire” being cast into the sea, it can evoke a cataclysmic vision of God’s formidable power, reminiscent of other biblical displays of divine judgment.

Interestingly, one cannot help but recall the plagues of Egypt from the book of Exodus, where the Nile River turned to blood. Both scenarios evoke deep themes of life, sustenance, and eventual destruction, laying a groundwork that spans biblical history. Water, essential for life, conflicts with its symbolic transformation into blood, which often suggests violence or loss—a potent mechanization of divine retribution.

In biblical literature, God often uses water to convey cleansing and life, yet here, its transformation reflects the weight of judgment. The balance between creation and destruction embodies a recurring motif in seemingly disastrous events. Diagrams of the cosmic struggle, especially seen through Isaian and prophetic literature, echo the divine seriousness regarding environmental care—when creation reflects dilution of moral order; even ecosystems become entities pointing toward eternal truths.

This imagery reminds followers of the interconnectedness of nature and spirituality and serves as a potent prompt for reflection on humanity's parallel actions and their echoes throughout time.