Saitama vs. Evil Natural Water

Saitama vs. Evil Natural Water was the battle between Saitama and the Monster Association executive, Evil Natural Water.

Prelude
Having absorbed huge quantities of water from the ocean, Evil Natural Water has increased exponentially in size and become known as Evil Ocean Water. While Evil Ocean Water assists Sage Centipede in fighting Garou, and seemingly takes down the Human Monster with its Ocean Grand Cannon, Saitama rushes towards the water entity while running across the ocean.

Battle
Upon coming close enough, Saitama jumps towards Evil Ocean Water, unleashes a mighty Serious Punch against the monster. Evil Ocean Water is then dispersed entirely by the powerful punch from the hero, with the ocean being split in half in the process.

Aftermath
As a consequence of Evil Natural Water defeat, the large body of water that envolved the entire ocean began to collapse, and Saitama had to conduct an aircraft carrier to land by surfing it. After leaving the aircraft carrier near where Fubuki and the New Blizzard Group were, Sage Centipede's carcass lands right on top of it shortly after saitama jumps to find Garou in the middle of the pool of debris of the Monster Association.

Trivia

 * This is the third time in the One-Punch Man manga that Saitama has used a Serious Punch to defeat an enemy.